Asteraceae

HOST LISTS AND KEYS FOR EACH PLANT GENUS

(in alphabetical order)

Obe-Par

Oberna

Obione

Ochetophila

Ochna

Ochradenus

Ochroma

Ochthodium

Ocimum

Ocotea

Octadesmia

Octomeron

Ocymum

Odontioda

Odontites

Odontoglossum

Odontonema

Odontospermum

Oedibasis

Oemleria

Oenanthe

Oenocarpus

Oenothera

Ohwia

Oldenlandia

Oldfeltia

Olea

Olearia

Oligostachyum

Oligotrichum

Omalotheca

Oncidium

Oncoba

Oncosiphon

Onobrychis

Onoclea

Ononis

Onopordum

Onosma

Onosmodium

Onychium

Ophiopogon

Ophiorrhiza

Ophiuros

Ophrys

Oplismenus

Oplopanax

Opopanax

Opulaster

Opuntia

Orchis

Oreocnide

Oreopanax

Origanum

Orixa

Orlaya

Ormenis

Ornithidium

Ornithogalum

Ornithopus

Orobanche

Orostachys

Ortantha

Orthilia

Orthocarpus

Orthostemon

Oryza

Oryzopsis

Osbeckia

Osmanthus

Osmaronia

Osmia

Osmorhiza

Osmunda

Osmundastrum

Osteomeles

Osteospermum

Ostericum

Ostrya

Ostryoderris

Ostryopsis

Othonna

Othonnopsis

Otites

Otochilus

Ottelia

Ourisia

Ourouparia

Oxalis

Oxybaphus

Oxycoccus

Oxydendrum

Oxylobium

Oxylobus

Oxypetalum

Oxypogon

Oxyria

Oxytropis

Ozoroa

Ozothamnus

Pachira

Pachycarpus

Pachylophis

Pachypleurum

Pachystachys

Pachystima

Packera

Padus

Paederia

Paeonia

Palaquium

Palicourea

Palisota

Paliurus

Pallenis

Palura

Panax

Pandanus

Pandiaka

Pandorea

Panicularia

Panicum

Panzeria

Panzerina

Papaver

Paphiopedalum

Pappea

Pappobolus

Parabenzoin

Parageum

Parahebe

Paraixeris

Parasenecio

Parathelypteris

Paratropia

Pardanthopsis

Parentucellia

Parietaria

Parinari

Parkia

Parkinsonia

Parmena

Parmentiera

Parodichloa

Paronychia

Parrotia

Parsonsia

Parthenium

Parthenocissus

Oberna	Caryophyllaceae
Oberna behen = Silene vulgaris
O. multifida	Macrosiphum eastopi, stellariae
O. wallichiana	Aphidura ornatella; Aphis craccivora;
	Brachycolus cucubali

Use key to apterae on Silene.

Obione see Atriplex

Amaranthaceae

Ochetophila	Rhamnaceae
Ochetophila nana	Aphis conflicta
O. trinervis	Aphis conflicta

Ochna	Ochnaceae
A single aphid species, Sitobion ochnearum, is recorded from 4 spp. of Ochna; O. afzelii, O. leptoclada, O. pretoriensis, O. pulchra.

Ochradenus	Resedaceae
Ochradenus baccatus	Myzus persicae

Ochroma	Bombacaceae
Ochroma lagopus	Aphis gossypii

Ochthodium	Brassicaceae
Ochthodium aegyptiacum	Brevicoryne brassicae

Ocimum	Lamiaceae
Ocimum americanum	Aphis gossypii
O. basilicum	Aphis [affinis], craccivora, fabae, gossypii;
	Aulacorthum solani; Macrosiphum mesosphaeri;
	Myzus ornatus, persicae; Neomyzus circumflexus;
	[Ovatus crataegarius]; Sitobion colei
O. canum = O. americanum
O. gratissimum	Aphis gossypii; Aulacorthum solani;
	Macrosiphum mesosphaeri, salviae; Myzus ornatus
O. minimum	Myzus ornatus
O. obovatum	Aphis gossypii
O. sanctum = O. tenuiflorum
O. tenuiflorum	Aphis gossypii; Macrosiphum mesosphaeri; Myzus ornatus
O. urticifolium = O. gratissimum
Ocimum sp.	Aphis spiraecola; [Sitobion indicum]

Key to apterae on Ocimum:-

1	SIPH mainly or wholly dark, with a subapical zone of reticulation (at least 4-5 rows of closed polygonal cells)	…..2
–	SIPH pale or dark, without subapical polygonal reticulation	…..go to key to polyphagous aphids

2	ANT and tibiae mainly pale. Dorsum with an extensive solid dark shield across ABD TERG 1-5, fused with marginal and antesiphuncular sclerites. Longest hairs on ANT III less than 0.5 × BD III	…..Sitobion colei
–	ANT and tibiae mainly dark. Dorsum without a complete dark shield, with or without a less extensive dark patch. Longest hairs on ANT III more than 0.5 × BD III	…..3
3	Dorsal abdomen with a central dark patch. Head as dark as ANT. SIPH wholly dark. Process at base of prothoracic furca is tubercular, about as long as its basal width	…..Macrosiphum salviae

–

Dorsal abdomen without a dark central patch. Head paler than ANT. SIPH usually with paler basal section. Process at base of prothoracic furca is broadly conical, much shorter than its basal width

…..Macrosiphum mesosphaeri

Ocotea	Lauraceae
Ocotea acutifolia	Lizerius ocoteae
O. glomerata (?)	Lizerius pustulatus
O. porphyria	Lizerius ocoteae
Ocotea sp.	Aphis (Toxoptera) aurantii; Lizerius tuberculatus

Key to species:-

1	Body of aptera with conical, club-shaped or crown-shaped processes	…..2
–	Body of aptera without processes	…..go to key to polyphagous aphids
2	ABD TERG 1-5 each with 6 sclerites, the marginal ones developed into short conical processes, and transverse bars on ABD TERG 6-8; ABD TERG 8 bearing 2 large conical processes and 2-4 much smaller ones (fig. 63A). Antenna of aptera 6-segmented	…..Lizerius ocoteae
–	Dorsal body membranous, with numerous short spinulose club-shaped or crown-shaped processes. ABD TERG 8 with 4 tapering or finger-like processes (e.g. fig. 63B). Antennae of aptera often 5-segmented	…..3
3	Aptera with apical diameter of largest spinal process on ABD TERG V c. 30 μm, about as wide as SIPH pore. Processes are finger-like/tapering only on ABD TERG 8. Alata with ANT III bearing 8-17 secondary rhinaria in a row, and ANT PT/BASE 0.18-0.29	…..Lizerius tuberculatus

–

Aptera with apical diameter of largest spinal process on ABD TERG V c. 20 μm, about 0.5 of width of SIPH pore. Marginal processes are finger-like/tapering on ABD TERG (4-)5-7. Alata with ANT III bearing 15-26 secondary rhinaria scattered all over segment, and ANT PT/BASE 0.30-0.36

…..Lizerius pustulatus

Octadesmia see Dilomilis

Orchidaceae

Octomeron see Platostoma

Lamiaceae

Ocymum see Ocimum

Lamiaceae

×Odontioda	Orchidaceae
×Odontioda sp. (hybrid)	Aphis spiraecola

Odontites (including Orthantha)	Orobanchaceae
Odontites lutea	Brachycaudus mimeuri, persicae
O. purpureus	Brachycaudus helichrysi
O. serotina = O. vulgaris
O. sicula	Brachycaudus mimeuri
O. verna	Brachycaudus mimeuri
O. vulgaris	Aphis frangulae, sibirica; Brachycaudus persicae

Key to apterae on Odontites:-

1	Cauda short and rounded, not longer than its basal width	…..2
–	Cauda finger-like, longer than its basal width	…..3
2	Dorsum with an extensive solid black shield covering almost all of metanotum and ABD TERG 1-6	…..Brachycaudus mimeuri (or persicae: see text)
–	Dorsum without an extensive solid black shield	…..Brachycaudus helichrysi
3	SIPH 0.4-0.9 × cauda, which is as dark as SIPH and bears 7-19 hairs …..Aphis sibirica
–	SIPH (0.8-)0.9-2.1 × cauda, which is usually paler than SIPH and bears 4-11(-13) hairs	….Aphis frangulae group (or try key to polyphagous aphids)

Odontoglossum	Orchidaceae
Odontoglossum sp.	Sitobion luteum

(or try key to orchid-feeding aphids under Cymbidium)

Odontonema	Acanthaceae
Odontonema strictum	Myzus persicae

Odontospermum see Asteriscus

Asteraceae

Oedibasis	Apiaceae
Oedibasis platycarpa	Aphis craccivora

Oemleria (including Osmaronia)	Rosaceae
Oemleria cerasiformis	Macrosiphum [euphorbiae], occidentale, osmaroniae

Key to apterae on Oemleria:-

–	R IV +V short and blunt, about as long as its basal width, 0.7-0.8 × HT II. ANT BASE VI 1.5-2.3 × R IV+V. Cauda with 8-14 hairs	…..Macrosiphum occidentale
–	R IV+V much longer than its basal width, 0.9-1.1 × HT II. ANT BASE VI 1.0-1.5 × R IV+V. Cauda with 5-8 hairs	…..Macrosiphum osmaroniae

Oenanthe	Apiaceae
Oenanthe aquatica	Anuraphis subterranea; Aulacorthum solani;
	Cavariella aegopodii; Pemphigus protospirae
Oe. crocata	Aphis fabae; Cavariella aegopodii, pastinacae, theobaldi;
	Hyadaphis passerinii; Macrosiphum euphorbiae;
	Myzus persicae
Oe. javanica	Amphorophora cryptotaeniae;
	Aphis craccivora, gossypii, spiraecola;
	Brachycaudus helichrysi; Cavariella oenanthi, salicicola;
	[Hyalopterus pruni]; Myzus persicae; Semiaphis heraclei
Oe. pimpinelloides	Aphis fabae, spiraecola; Dysaphis apiifolia;
	Hyadaphis passerinii
Oe. sarmentosa	Cavariella aegopodii, konoi; Hyadaphis passerinii;
	Pemphigus populicaulis
Oe. silaifolia	Cavariella aegopodii; Macrosiphum euphorbiae
Oe. stolonifera = Oe.javanica
Oenanthe spp.	[Aphis oenanthis Lichtenstein (nomen nudum)];
	Cavariella salicis

Key to apterae on Oenanthe:-

1	ABD TERG 8 with a posteriorly projecting process above cauda bearing 2 hairs (e.g. Fig 10g); in 1 species (Cavariella oenanthi) this is reduced to a small warty knob in the centre of ABD TERG 8, with 2 associated hairs (Fig. 10i)	…..2
–	No supracaudal process, nor are there 2 hairs on ABD TERG 8 close together and associated with a warty knob	…..8
2	SIPH clavate; swollen on distal half to at least 1.2 × narrowest part of basal half. ANT PT/BASE 0.6-2.0	…..3
–	SIPH tapering or cylindrical, or with slight subapical swelling. ANT PT/BASE 1.3-3.5	.….6

3	Supracaudal process conical or finger-like, not projecting to tip of cauda	…..4
–	Supracaudal process large, conical, extending beyond and usually covering cauda	…..6
4	ANT PT/BASE 2.6-4.0	…..Cavariella pastinacae
–	ANT PT/BASE 0.6-2.0	…..5
5	ANT PT/BASE 0.6-1.3. R IV+V 0.7-0.95 × HT II, and without accessory hairs	.….Cavariella aegopodii
–	ANT PT/BASE 1.35-2.0. R IV+V 1.0-1.2 × HT II, with 2 accessory hairs	…..Cavariella konoi
6	R IV+V 1.05-1.2 × HT II. SIPH short and stout, narrowing only at base	…..Cavariella salicicola

–	R IV+V 0.85-1.04 × HT II. SIPH with narrower basal stem extending over about 0.3 of length	…..Cavariella salicis
7	Supracaudal process reduced to a warty knob, distinctly shorter than ANT II (Fig. 10i). Head and Cauda dark, tergum with variably developed dark markings. Secondary rhinaria sometimes present on ANT III-V or IV-V (of aptera). ANT PT/BASE 1.3-1.8. Femoral hairs numerous, long and fine, longer than 0.5 × width of hind femur	…..Cavariella oenanthi
–	Supracaudal process at least as long as ANT II. Head and cauda pale, tergum without dark markings. Antennae (of aptera) without secondary rhinaria. ANT PT/BASE 2.1-3.5. Femoral hairs sparse and shorter than 0.5 × width of hind femur	…..Cavariella theobaldi
8	SIPH very small and flangeless; less than 0.5 × cauda and often not much longer (1.0-1.8 ×) than their diameter at midlength	…..Semiaphis heraclei
–	SIPH (if present at all) more than 0.6 × cauda, and with a flange	…..9
9	Cauda helmet-shaped, a little shorter than its basal width. Spinal tubercles (STu) present on head and at least ABD TERG 8	…..10
–	Cauda (if developed at all) tongue- or finger-shaped and distinctly longer than its basal width. STu usually not evident	…..11
10	SIPH less than 2 × basal width with close-set rows of spinules. Cauda with c.10-12 hairs	…..Anuraphis subterranea
–	SIPH more than 2 × basal width with normal imbrication. Cauda with 5 hairs	…..Dysaphis apiifolia
11	SIPH and cauda both dark, with SIPH swollen on distal 0.7, and 0.9-1.4 × cauda	…..Hyadaphis passerinii

–	Without that combination of characters	…..12
12	SIPH strongly clavate, with swollen part maximally 1.8-2.1 × minimum width on basal part, and with a subapical constriction bearing 2-3 rows of tranverse striae below the well-developed flange. R IV+V 1.5-1.7 × HT II. Apex of ANT PT pointed	…..Amphorophora cryptotaeniae

–

Without that combination of characters

…..go to key to polyphagous aphids

Oenocarpus	Arecaceae
Oenocarpus distichus	Cerataphis brasiliensis

Oenothera	Onagraceae
Oenothera affinis	Aphis oenotherae
Oe. amoena = Clarkia amoena
Oe. berteroana = Oenothera affinis
Oe. biennis	Anoecia [cornicola], oenotherae, [setariae];
	Aphis fabae, frangulae, gossypii, grossulariae,
	holoenotherae, nasturtii, oenotherae, oestlundi;
	Aulacorthum solani; Brachycaudus cardui;
	Macrosiphum euphorbiae, gaurae, [pallidum];
	Myzus [biennis], oenotherae, persicae;
	[Pemphigus oenotherae (nomen nudum)];
	[Uroleucon ambrosiae]
Oe. brevihypanthialis = Oe. deflexa var. brevihypanthialis
Oe. casimiri	Aphis holoenotherae
Oe. cespitosa = Pachylophis cespitosa
Oe. deflexa	Aphis holoenotherae
(incl. var. brevihypanthialis)
Oe. erythrosepala = Oenothera glazioviana
Oe. flaemingina	[Aphis sp. nr. holoenotherae – Rakauskas 2008]
Oe. flava	[Protaphis middletonii]
Oe. fruticosa = Kneiffia fruticosa
Oe. glazioviana	Aphis epilobiaria, oenotherae, spiraecola;
	[Macrosiphum rosae]; Myzus ornatus;
	[Uroleucon nigrotuberculatum]
Oe. grandiflora = Oenothera glazioviana
Oe. hazelae var. subterminalis	Aphis holoenotherae
Oe. javanica	Aphis spiraecola
Oe. lamarckiana	Aphis holoenotherae, oenotherae
Oe. megallanica	Aphis grossulariae
Oe. missouriensis = Megapterium missouriense
Oe. muricata = Oenothera biennis
Oe. oakesiana	Aphis holoenotherae, oenotherae
Oe. odorata	Aphis gossypii, oenotherae, spiraecola;
	Rhopalosiphoninus staphyleae
Oe. parviflora	Aphis oenotherae
Oe. perangusta × biennis	Aphis holoenotherae
Oe. picensis	Aphis spiraecola
Oe. pilosella = Kneiffia pilosella
Oe. rosea	Rhopalosiphoninus staphyleae
Oe. rubricauloides	Aphis holoenotherae
Oe. sarmentosa	[Cavariella aegopodii]
Oe. serrulata = Calylophus serrulata
Oe. spectabilis	Aphis oenotherae
Oe. stricta	Aphis oenotherae
Oe. strigosa var. subulifera	Myzus oenotherae
Oe. stuchii	[Aphis sp. nr holoenotherae – Rakauskas 2008]
Oe. subterminalis = Oenothera hazelae var. subterminalis
Oe. subulifera = Oenothera strigosa var. subulifera
Oe. versicolor	Brachycaudus helichrysi
Oenothera sp.	Aphis praeterita, sambuci;
	[Protaphis sp. (Utah, USA; A. Jensen, aphidtrek.org)

Key to apterae on Oenothera:-

1	ANT PT/BASE less than 0.5, with numerous long hairs. SIPH as large pores with surrounding hairs on shallow pigmented cones	…..Anoecia oenotherae
–	ANT PT/BASE more than 1.4, with few hairs. SIPH tubular	…..2
2	ANT tubercles undeveloped or weakly developed, so that front of head is convex, straight or sinuous in dorsal view	…..3
–	ANT tubercles well developed, so there is a deep frontal sinus in dorsal view	…..16
3	Cauda helmet-shaped, not longer than its basal width, with 4-8 hairs. SIPH have a distinct annular subapical incision. Spiracular apertures are large and rounded. ABD TERG 1 and 7 are without marginal tubercles (MTu)	…..4
–	Cauda tongue-shaped, as long as or longer than its basal width, with 4-21 hairs. SIPH without a subapical annular incision. Spiracular apertures reniform. ABD TERG 1 and 7 with MTu	…..5

4	Dorsal abdomen with an extensive solid black shield. ANT III 0.31-0.47 mm, 2.4-3.4 × HT II. R IV+V 0.17-0.24 mm. SIPH dark, imbricated, 1.7-3.4 × cauda …..Brachycaudus cardui
–	Dorsal abdomen without a black shield. ANT III 0.07-0.25 mm, 0.9-2.2 × HT II. R IV+V 0.10-0.15 mm. SIPH pale, smooth, 0.8-2.0 × cauda	……Brachycaudus helichrysi
5	Cauda bluntly triangular, about as long as its basal width or only a little longer. ANT III with (0-)1-12 rhinaria on distal half	…..Protaphis middletonii
–	Cauda tongue-shaped, distinctly longer than its basal width. ANT III without rhinaria (except in alatiform specimens)	…..6
6	SIPH 2.2-4.5 × cauda, which is black and bears 9-20 hairs. ABD TERG 2-4(-6) as well as 1 and 7 with well-developed MTu	…..Aphis sambuci
–	SIPH 0.7-2.5 × cauda, if more than 2.1 × then cauda is pale or dusky and bears fewer hairs. ABD TERG 2-6 with or without small MTu	…..7
7	SIPH pale. R IV+V 0.13-0.18 mm long, with 5-12 accessory hairs. Cauda with 8-24 hairs	…..8

–	SIPH pale, dark, or dark-tipped. R IV+V 0.075-0.145 mm long, with 2 accessory hairs. Cauda with 4-24 hairs	…..11
8	ABD TERG 2-6 mostly with MTu, as well as ABD TERG 1 and 7	…..Aphis grossulariae
–	ABD TERG 2-6 without MTu	…..9
9	Tarsi almost completely smooth. Cauda with 16-24 hairs	…..Aphis epilobiaria
–	Tarsi distinctly imbricated. Cauda with 8-16 hairs	…..10
10	ANT PT/BASE 1.9-2.5 (usually more than 2)	…..Aphis oenotherae
–	ANT PT/BASE 1.5-2.3 (usually less than 2)	…..Aphis holoenotherae
11	ANT PT/BASE 3.3-4.7. Cauda with 5-8 hairs	…..Aphis praeterita
–	ANT PT/BASE 1.2-3.5 (if more than 3.1 then cauda has 11-24 hairs)	…..12
12	ANT PT/BASE 1.2-1.9. R IV+V 1.35-1.7 × HT II. Anterior half of subgenital plate with 4-6 hairs	…..Aphis oestlundi
–	ANT PT/BASE 1.9-3.5. R IV+V 0.9-1.4 × HT II. Anterior half of subgenital plate with 2-9 hairs	…..13
13	SIPH pale except at apices	.….Aphis nasturtii
–	SIPH dark	…..14
14	SIPH clearly darker than cauda, which bears 4-8 hairs. Longest hind femoral hairs only 0.4-0.7 × diameter of trochantro-femoral suture	……Aphis gossypii
–	Cauda always dark like SIPH, and bearing 7-24 hairs. Longest hind femoral hairs usually more than 0.7 × diameter of trochantro-femoral suture	…..15
15	Dorsal abdomen without any dark markings. Cauda usually with a midway constriction, and bearing 7-15 hairs	…..Aphis spiraecola
–	Dorsal abdomen with dark bands on ABD TERG 8, or 7 and 8, and often with dark markings anterior to SIPH. Cauda without any midway constriction, and bearing 11-24 hairs	…..Aphis fabae
16	SIPH with subapical reticulation (at least 4-5 rows of closed polygonal cells). Head smooth, with inner faces of ANT tubercles divergent	…..17
–	SIPH without subapical polygonal reticulation. Head spiculose, with inner faces of ANT tubercles parallel or apically convergent	…..18
17	SIPH variably pigmented, often dark distally. ANT VI BASE 0.65-0.95 × R IV+V. R IV+V 1.1-1.3 × HT II	…..Macrosiphum gaurae
–	SIPH usually pale, or only dusky at apices. ANT VI BASE 0.9-1.3 × R IV+V. R IV+V 0.85-1.1 × HT II	…..Macrosiphum euphorbiae
18	Longest hairs on ANT III more than 0.5 × BD III (?). ANT dark beyond basal half of ANT V. SIPH 1.4-1.9 × cauda (?)	…..Myzus biennis (or oenotherae? – see text)*
–	Longest hairs on ANT III less than 0.5 × BD III. ANT pale except for segmental apices. SIPH 1.9-2.5 × cauda	…..19
19	ANT III with (0-) 1-2 (-3) small rhinaria near base. Inner faces of ANT tubercles approximately parallel-sided. SIPH tapering/cylindrical on distal half	…..Aulacorthum solani

–

ANT III without rhinaria. Inner faces of ANT tubercles apically convergent. SIPH slightly swollen on distal half

…..Myzus persicae

Ohwia	Fabaceae
Ohwia caudata	Aphis gossypii

Oldenlandia	Rubiaceae
Oldenlandia corymbosa	Aphis gossypii; Myzus persicae
O. herbacea	Aphis gossypii
O. sclerophylla	Aphis gossypii
Oldenlandia spp.	[Acyrthosiphon pisum]; Aulacorthum solani;
	[Lipaphis pseudobrassicae]; Myzus cymbalariae;
	Uroleucon compositae

Use key to polyphagous aphids.

Oldfeltia	Asteraceae
Oldfeltia polyphlebia see Senecio polyphlebius

Olea Olives	Oleaceae
Olea europaea	Prociphilus oleae; [Tetraneura agnesii del Guercio 1920]

Olearia	Asteraceae
Olearia bullata	[Aphis sp. near coprosmae (New Zealand; Teulon et al. 2013)]
O. gunniana	Aphis gossypii; [Uroleucon sp. (Leonard 1972a)]
O. lirata	[Uroleucon sp. (Leonard 1972a)]
O. passerinoides	Myzus persicae; [Uroleucon sp. (Leonard 1972a)]
O. pimeleoides	[Uroleucon sp. (Leonard 1972a)]
O. viscidula	Myzus persicae; [Uroleucon sp. (Leonard 1972a)]

Use key to polyphagous aphids. (Note: the Uroleucon is a large, red, apparently undescribed species.)

Oligostachyum	Poaceae
Oligostachyum shiuyingianum	Ceratovacuna hoffmanni; Chaitoregma tattakana

Use key to aphids on Arundinaria.

Oligotrichum	Polytrichaceae
Oligotrichum aligerum	Myzodium modestum

Use key to apterae of moss-feeding aphids under Polytrichum.

Omalotheca	Asteraceae
Omalotheca caucasica = Gnaphalium sylvaticum

Oncidium	Orchidaceae
Oncidium altissimum	Cerataphis orchidearum; Myzus persicae; Sitobion luteum
O. cebolleta = Trichocentrum cebolleta
O. sphacelatum	Aphis (Toxoptera) aurantii

Use key to apterae on orchids under Cymbidium.

Oncoba	Salicaceae
Oncoba spinosa	Aphis (Toxoptera) aurantii; Schoutedenia ralumensis

Key to apterae on Oncoba:-

–	ABD TERG 7 with a pair of long, pointed backwardly-directed processes. SIPH as short broad cones. ANT 5-segmented. ANT PT/BASE less than 1	.…Schoutedenia ralumensis
–	ABD TERG 7 without long processes. SIPH tubular, dark, much longer than wide. ANT 6-segmented, with ANT PT/BASE 3.5-5.0	….. Aphis (Toxoptera) aurantii

Oncosiphon	Asteraceae
Oncosiphon piluliferum	Aphis craccivora

Onobrychis	Fabaceae
Onobrychis arenaria ssp. sibirica	Aphis craccivora
O. argentea ssp. hispanica = O. conferta ssp. hispanica
O. conferta ssp. hispanica	Aphis craccivora
O. cyri	Aphis craccivora
O. gracilis	Acyrthosiphon pisum
O. kachetica	Acyrthosiphon pisum; Aphis craccivora, fabae;
	Therioaphis trifolii
O. micrantha	Aphis craccivora
O. montana	Acyrthosiphon pisum; Aphis craccivora
O. pulchella	Aphis craccivora, [ “laburni” (= cytisorum?)]
O. sativa = O. viciifolia
O. sibirica = O. arenaria ssp. sibirica
O. squarrosa	Acyrthosiphon pisum
O. tanaitica (= O. arenaria)	Aphis craccivora
O. transcaucasica	Aphis craccivora
O. viciifolia	Acyrthosiphon loti, pisum;
	Aphis [craccae], craccivora, fabae, pseudocomosa;
	[Brachycaudus persicae]; Therioaphis trifolii
Onobrychis sp.	[Smynthurodes betae]

Key to apterae on Onobrychis:-

1

Fore coxae greatly enlarged. SIPH in form of truncate cones. Cauda knobbed, anal plate bilobed. Dorsal hairs with expanded apices, and arising from pigmented, tuberculate bases

.….Therioaphis trifolii

–	Fore coxae normal. SIPH tubular. Cauda tongue- or finger-shaped, anal plate entire. Dorsal hairs with blunt or pointed apices, not arising from tuberculate bases	..…2
2	Body pale, spindle-shaped; BL 2.0-4.4 mm. ANT tubercles well developed with inner faces divergent. SIPH and cauda pale	…..3
–	Body oval, with an extensive dark dorsal shield; BL 1.4-2.2 mm. ANT tubercles weakly developed. SIPH and cauda both dark	…..4
3	ANT I longer than wide and bearing 9-23 hairs. SIPH attenuate distally, thinner than hind tibia at midlength	…..Acyrthosiphon pisum
–	ANT I not longer than wide, bearing 6-10 hairs. SIPH not attenuate distally, as thick as or thicker than hind tibia at midlength	…..Acyrthosiphon loti
4	Longest ANT hairs 0.67-1.4 × ANT BD III. Femoral hairs about as long as trochantro-femoral suture. Cauda with 8-19 hairs (rarely less than 10)	…..Aphis pseudocomosa
–	Longest ANT hairs 0.37-0.75 × ANT BD III. Femoral hairs shorter. Cauda with 4-9 hairs	…..Aphis craccivora

Onoclea	Woodsiaceae
Onoclea sensibilis	Amphorophora ampullata, ampullata ssp. laingi;
	Aulacorthum solani; Neomyzus circumflexus
O. struthiopteris see Matteuccia

Use key to fern-feeding aphids under Polypodium.

Ononis	Fabaceae
Ononis alba	Therioaphis obscura
O. antiquorum = O. spinosa ssp. antiquorum
O. aragonensis	Aphis fabae
O. arvensis = O. spinosa ssp. hircina
O. austriaca = O. spinosa ssp. austriaca
O. diffusa	Therioaphis ononidis
O. fruticosa	Acyrthosiphon loti, ononis; Aphis brunnea
O. hircina = O. spinosa ssp. hircina
O. leiosperma = O. spinosa ssp. leiosperma
O. minutissima	Aphis craccivora; Therioaphis alatina
O. natrix (incl. sspp.	Acyrthosiphon pilosum, pisum;
angustissima, ramosissima)	Aphis brunnea, craccivora, [medicaginis];
	[Myzus persicae]; Therioaphis alatina, natricis, trifolii
O. pseudohircina = spinosa ssp. hircina
O. pubescens	Aphis brunnea
O. pusilla	Therioaphis alatina
O. ramosissima = natrix ssp. ramosissima
O. reclinata	Therioaphis obscura
O. repens	Acythrosiphon loti, ononis, pisum; Aphis kaltenbachi;
(= O. spinosa ssp. procurrens)	Macrosiphum euphorbiae; Therioaphis ononidis, trifolii
O. repens var. mitis = O. spinosa ssp. hircina
O. serrata	Therioaphis ononidis
O. spinosa	Acyrthosiphon ononis, pilosum, pisum;
(incl. ssp. antiquorum, austriaca, Aphis brunnea, craccivora, cytisorum, kaltenbachi, hircina)
	?medicaginis;
	Brachycaudus helichrysi; Macrosiphum euphorbiae;
	[Myzus sp. (Bozhko 1976a)];
	Therioaphis alatina, hungarica, natricis, obscura,
	ononidis, trifolii
O. stenophylla	Therioaphis natricis
O. tridentata	Aphis cytisorum, kaltenbachi, ononidis
O. viscosa	Aphis brunnea; Therioaphis alatina

Key to apterae on Ononis:-

(Couplets 1-3 can be applied to alatae as well as apterae.)

1	Fore coxae greatly enlarged. SIPH in form of truncate cones. Cauda knobbed, anal plate bilobed. Dorsal hairs with expanded apices, and arising from tuberculate bases that are often pigmented	.….2
–	Fore coxae normal. SIPH tubular. Cauda tongue- or finger-shaped, anal plate entire. Dorsal hairs with blunt or pointed apices, not arising from tuberculate bases	..…7
2	ABD TERG 1-4 each bearing 7-10 (mostly 8) long hairs	…..Therioaphis trifolii
–	ABD TERG 1-4 each with 4 long hairs (one spinal pair and one marginal pair; occasionally there are also one or two much smaller hairs)	…..3
3	R IV+V distinctly longer than HT II, and bearing 8-27 accessory hairs	…..4
–	R IV+V 0.7-0.95 × HT II, and bearing 2-8 (-9) accessory hairs	…..6
4	All adult viviparae alate. ABD TERG 8 with 2 (-3) hairs. (R IV+V with 17-25 accessory hairs)	…..Therioaphis alatina
–	Predominant morph apterous. ABD TERG 8 with 4-6 hairs	…..5
5	R IV+V with 14-27 accessory hairs	…..Therioaphis natricis
–	R IV+V with 8-12 accessory hairs	…..Therioaphis ononidis
6	ABD TERG 1-7 with very large paired variably pigmented sclerotic cross-bars, often fused across midline. R IV+V with 2-4 accessory hairs	…..Therioaphis obscura
–	ABD TERG 1-7 with hairs arising from separate sclerotic plates that are rarely fused across midline. R IV+V with 6-9 accessory hairs	…..Therioaphis hungarica
7	Body spindle-shaped. ANT tubercles well developed, with inner faces smooth and divergent. ANT often longer than BL	…..8
–	Body oval. ANT tubercles undeveloped or weakly developed, ANT shorter than BL …..12
8	SIPH with subapical polygonal reticulation. Longest hairs on ANT III more than 0.5 × basal diameter of segment	…..Macrosiphum euphorbiae
–	SIPH without subapical polygonal reticulation. Longest hairs on ANT III usually less than 0.5 × basal diameter of segment	…..9
9	R IV+V with 19-36 accessory hairs. First tarsal segments usually with 5 hairs. Prominent marginal tubercles present on several of ABD TERG 2-4(-5)	…..Acyrthosiphon pilosum
–	R IV+V with 3-12 accessory hairs. First tarsal segments with 3 hairs. Abdominal marginal tubercles either absent or small and inconspicuous	…..10
10	ANT I with 6-9 hairs. ANT BASE VI 1-1.5 × longer than R IV+V. SIPH not attenuate distally; diameter at midlength greater than middle diameter of hind tibia	..…Acyrthosiphon loti

–	ANT I with 9-23 hairs. ANT BASE VI 1.6-2.9 × longer than R IV+V. SIPH attenuate distally, with diameter at midlength similar to or less than middle diameter of hind tibia	..…11
11	ANT VI BASE 1.6-1.9 × R IV+V, which bears (6-) 8-12 accessory hairs. R IV+V 0.75-0.95 × HT II. Cauda with 11-23 hairs	…..Acyrthosiphon ononis
–	ANT VI BASE 1.9-2.9 × R IV+V which bears 3-7 (-8) accessory hairs. R IV+V 0.67-0.85 × HT II. Cauda with 8-14 hairs	…..Acyrthosiphon pisum
12	Cauda helmet-shaped, not longer than its basal width. SIPH pale, smooth, with a subapical annular incision. Spiracular apertures large and rounded. ABD TERG 1 and 7 without marginal tubercles (MTu). Dorsal abdomen without dark markings	…..Brachycaudus helichrysi

–	Cauda tongue- or finger-shaped, longer than its basal width. SIPH dark, imbricated, without a subapical annular incision. Spiracular apertures reniform. ABD TERG 1 and 7 always with MTu. Dorsal abdomen usually with dark markings	…..13
13	SIPH very short, flangeless, 0.2-0.3 × cauda. Dorsum usually with a solid dark shield from metanotum to ABD TERG VI	…..Aphis kaltenbachi
–	SIPH with a distinct flange, and at least 0.8 × cauda. Dorsum with or without a solid dark shield	…..14
14	Very short haired; hairs on ABD TERG 8 are 11-16 μm, and on ABD TERG 3 marginally 11-12 μm. Posterior hair on hind trochanter 16-24 μm, 0.29-0.52 × length of trochantro-femoral suture	…..Aphis ?medicaginis (see text)
–	Longer haired; hairs on ABD TERG 8 are 18-85 μm, and on ABD TERG 3 marginally 12-85 μm. Posterior hair on hind trochanter (0.34-) 0.5-2.0 × length of trochantro-femoral suture	…..15

15	ABD TERG 1-4 and 7, and sometimes also 5 and 6, with MTu. R IV+V 1.1-1.45 × HT II and bearing 2-6 (usually 4-5) accessory hairs	…..Aphis brunnea
–	MTu only sporadically present on ABD TERG 2-4. R IV+V 0.9-1.2 × HT II, with 2 accessory hairs	…..16
16	Cauda with 11-25 hairs. Dorsal abdomen usually with a few small dark spots anterior to SIPH	…..Aphis fabae

–	Cauda with 4-13 hairs. Dorsal abdomen usually with extensive dark sclerotisation	…..17
17	R IV+V 0.88-1.16 × HT II (mostly 0.9-1.05 ×). Anterior half of genital plate with 2 (-3) hairs	…..Aphis craccivora

– R IV+V 0.97-1.3 × HT II (mostly 1.06-1.2 ×). Anterior half of genital plate with 2-8 hairs (mode 4, mean 5.2)

…..Aphis cytisorum

Onopordum	Asteraceae
Onopordum acanthium	Aphis craccivora, fabae, gossypii, solanella, [symphyti];
	Brachycaudus cardui, cardui ssp. turanica, helichrysi;
	Capitophorus carduinus, elaeagni;
	Dysaphis lappae ssp. cynarae; Macrosiphum euphorbiae;
	Myzus persicae;
	Protaphis anuraphoides, [elongata], pseudocardui,
	terricola;
	Trama troglodytes;
	Uroleucon aeneum, bicolor (?), [sonchi]
O. anisacanthum = O. heteracanthum
O. davisii	Aphis craccivora, spiraecola; Brachycaudus cardui
O. heteracanthum	Aphis fabae; Myzus persicae
O. illyricum	Aphis fabae; Brachycaudus cardui, helichrysi;
	Uroleucon aeneum, [sonchi]
O. leptolepis	Brachycaudus cardui; Protaphis [carthami], terricola
O. nervosum	Brachycaudus cardui
O. olgae	Pemphigus bursarius; Rectinasus buxtoni;
	Smynthurodes betae
O. sibthorpianum	Protaphis terricola
O. tauricum	Brachycaudus cardui

Key to apterae on Onopordum:-

1	SIPH absent. ANT PT/BASE less than 0.5. Eyes reduced, often to triommatidia	…..2
–	SIPH present. ANT PT/BASE more than 0.6. Eyes well-developed	…..5
2	Body and antennae sparsely hairy. Wax glands present on ABD TERG 3-7	…..Pemphigus bursarius

–	Body and antennae densely hairy, e.g. base of last antennal segment with more than 20 hairs. Wax glands absent or inconspicuous	…..3
3	HT II elongate, at least 0.5 × hind tibia. ANT 6-segmented …..Trama troglodytes
–	HT II of normal length. ANT 5-segmented	…..4
4	ANT V BASE and R IV+V both very long, respectively about 1.7 and 2.5 × width of head between antennal bases. ANT II similar in length to ANT I, much shorter than III	.….Rectinasus buxtoni
–	ANT V BASE and R IV+V of normal length , both about 0.5 × width of head between antennal bases. ANT II about twice as long as ANT I, similar in length to III	..…Smynthurodes betae

5	Cauda short, helmet-shaped or bluntly triangular, shorter than or not clearly longer than its basal width in dorsal view	…..6
–	Cauda elongate triangular, tongue-or finger-shaped, clearly longer than its basal width in dorsal view	…..11
6	ANT PT/BASE 0.75-1.15. Cauda bluntly triangular with 10-24 hairs. ABD TERG 1 and 7 with well-developed marginal tubercles (MTu)	…..7
–	ANT PT/BASE 2.3-5.1. Cauda helmet-shaped, with 5-8 hairs. If ABD TERG 1 and 7 have MTu then these are also present on ABD TERG 2-5	…..9
7	ANT III usually without secondary rhinaria (rarely with 1-3). (Longest hairs on ABD TERG 3 are 0.7-1.1 × ANT BD III)	…..Protaphis pseudocardui
–	ANT III and IV usually with rhinaria (0-12 on III and 0-4 on IV)	…..8
8	Longest hairs on ABD TERG 3 are 1.2-1.3 × ANT BD III. SIPH 0.9-1.2 × cauda, and with a distinct flange. R IV+V 1.45-1.65 × HT II	…..Protaphis anuraphoides
–	Longest hairs on ABD TERG 3 are 0.3-0.9 × ANT BD III. SIPH 0.67-0.92 × cauda, with a weak flange . R IV+V 1.2-1.4 (-1.5) × HT II	……Protaphis terricola
9	Dorsal abdomen with an extensive solid black patch. SIPH 0.10-0.15 × BL. Mesosternum with a pair of dark mammariform processes	…..Brachycaudus cardui
–	Dorsal abdomen without a solid black patch, at most with scattered dark markings. SIPH 0.05-0.10 × BL. Mesosternum without mammariform processes	…..10
10	BL 0.9-2.0 mm. SIPH smooth, short and broad-based, 1.5-2.0 × their diameter at midlength. Spinal and marginal tubercles (STu and MTu) rare or absent	……Brachycaudus helichrysi
–	BL 2.1-3.0 mm. SIPH imbricated and about 3 × their diameter at midlength. Numerous well-developed STu and MTu present	…..Dysaphis lappae ssp. cynarae
11	Hairs on front of head and dorsal body mostly long and capitate, and arising from tuberculate bases	…..12
–	Hairs on front of head and dorsal body not capitate	…..13
12	Cauda 1.1-1.5 × R IV+V, and bearing 5-8 hairs. ANT PT 3.1-4.4 × R IV+V, and ANT PT/BASE 4.6-6.3. SIPH without dark apices	…..Capitophorus carduinus
–	Cauda 1.4-2.3 × R IV+V, and bearing 7-13 hairs. ANT PT 4.5-6.3 × R IV+V, and ANT PT/BASE 6.0-9.2. SIPH with dark apices	…..Capitophorus elaeagni
13	BL 3.5-5.0 mm. ANT III with 17-45 rhinaria. SIPH dark, with reticulation extending over distal 0.15-0.25 of length	…..14
–	BL less than 3.5, and other characters not in that combination	…..go to key to polyphagous aphids

14	Cauda black. ABD TERG 2-4 consistently with well-developed MTu. R IV+V 1.2-1.3 × HT II	…..Uroleucon aeneum
–	Cauda pale. ABD TERG 2-3 irregularly with very small MTu. R IV+V 0.79-0.84 × HT II	…..Uroleucon bicolor (? – see text)

Onosma	Boraginaceae
Onosma stellulata	Brachycaudus cardui

Onosmodium	Boraginaceae
Onosmodium bejariense
var. occidentale	Brachycaudus helichrysi

Onychium	Adiantaceae
Onychium japonicum	Idiopterus nephrelepidis

Ophiopogon	Asparagaceae
Ophiopogon japonicus	Hydronaphis sp. (Japan – Moritsu 1983)

Ophiorrhiza	Rubiaceae
Ophiorrhiza sp.	Aphis spiraecola

Ophiuros	Poaceae
Ophiuros exaltatus	[Iowana zhangi]; Rhopalosiphum maidis

Ophrys	Orchidaceae
Ophrys apifera	Aphis fabae
O. fusca	Dysaphis neostroyani
O. sphegodes (incl. arenifera)	Aphis fabae
O. ×todaroana	Aphis fabae

Use key to apterae of orchid-feeding aphids under Cymbidium.

Oplismenus	Poaceae
Oplismenus burmannii	Hysteroneura setariae; Tetraneura akinire
O. compositus	Asiphonella dactyloni; [Ceratovacuna nekoashi];
	[Hyalomyzus raoi]; Hysteroneura setariae;
	Micromyzodium spinulosum; Pentalonia gavarri;
	Pseudoregma panicola; Sitobion miscanthi
O. hirtellus	Pseudoregma panicola
O. imbecillis = O. hirtellus
O. setarius = O. compositus
O. undulatifolius	[Ceratovacuna nekoashi]; Pseudoregma panicola;
	Sitobion akebiae
Oplismenus spp.	Baizongia pistaciae; Ceratovacuna lanigera;
	[Pseudoregma koshunensis]

Use key to apterae of grass-feeding aphids under Digitaria.

Oplopanax	Araliaceae
Oplopanax horridum	Aphis asclepiadis;
	Macrosiphum sp. nr euphorbiae (see aphidtrek.org)
Use key to polyphagous aphids.

Opopanax	Apiaceae
Opopanax chironius	Anuraphis pyrilaseri, shaposhnikovi; Aphis fabae;
	Dysaphis apiifolia

Key to apterae on Opopanax:-

(All 4 species have undeveloped or weakly-developed ANT tubercles, dark SIPH, dark cross-bands on ABD TERG 8 or 7-8, and usually some scattered dark markings on ABD TERG 1-6.)

1	Cauda distinctly longer than its basal width. Spinal tubercles (STu) absent, abdominal marginal tubercles (MTu) consistently present only on ABD TERG 1 and 7	…..Aphis fabae
–	Cauda helmet-shaped, a little shorter than its basal width. STu present on head and at least some ABD TERG, and MTu on ABD TERG 1-5 or 1-7	…..2
2	R IV+V much shorter than SIPH. SIPH more than 3 × basal width with normal imbrication. Cauda with 5 hairs	…..Dysaphis apiifolia
–	R IV+V longer than SIPH. SIPH less than 2.5 × basal width with close-set rows of spinules. Cauda with 11-18 hairs	…..3
3	MTu on ABD TERG 1-5 only. R IV+V 1.6-2.1 × HT II …..Anuraphis pyrilaseri
–	MTu on ABD TERG 1-7. R IV+V 1.2-1.6 × HT II	…..Anuraphis shaposhnikovi

Opulaster	Rosaceae
Opulaster malvaceus	Utamphorophora humboldti
O. opulifolius	Aphis neilliae, [pomi], spiraecola;
	[Chaetosiphon tetrarhodum]; Rhopalosiphum padi;
	Utamphorophora humboldti;
	[aphid gall – Wahlgren 1956, 51]

See key to apterae under Physocarpus.

Opuntia	Cactaceae
Opuntia aurantiaca	Protaphis middletonii
O. dillenii	Aphis gossypii
O. ficus-indica	Aphis craccivora, fabae; Myzus persicae;
	Protaphis middletonii
O. inermis = O. stricta
O. stricta	Pentalonia nigronervosa; Protaphis middletonii
O. vulgaris = O. ficus-indica
Opuntia sp.	Aphis gossypii

Key to apterae on Opuntia:-

–	ANT longer than BL, with ANT PT/BASE 5-8. Femora with basal 0.6 or more of length pale, rest contrastingly black. SIPH pale basally and dark distally. (Al. with broad-banded wing-veins, and radius fused with media to form a closed cell below pterostigma)	…..Pentalonia nigronervosa
–	Without that combination of characters	…..go to key to polyphagous aphids

Orchis	Orchidaceae
Orchis anthropophora	Aphis fabae
O. coriophora = Anacamptis coriophora
O. purpurea	Aphis orchidis
Orchis spp.	Aulacorthum solani; Dysaphis neostroyani;
	Myzus persicae; Neomyzus circumflexus

Use key to apterae of orchid-feeding aphids under Cymbidium.

Oreocnide (including Villebrunea)	Urticaceae
Oreocnide frutescens	Aulacorthum solani
O. integrifolia	[Greenidea bucktonis]

Oreopanax	Araliaceae
Oreopanax guatemalensis	Myzus persicae

Origanum (including Majorana)	Lamiaceae
Origanum compactum	Aphis sp. near gossypii
O. creticum = O. vulgare
O. heracleoticum = O. vulgare ssp. viridulum
O. majorana (= Majorana hortensis)	Myzus ornatus; Neomyzus circumflexus
O. ×paniculatum	Aphis origani
O. syriacum	Eucarazzia elegans
O. tyttanthum = O. vulgare ssp. gracile
O. virens = O. vulgare ssp. virens
O. vulgare (incl. sspp. gracile, virens, viridulum)	Aphis fabae, gossypii, nasturtii, origani;
	Aulacorthum solani; Kaltenbachiella pallida;
	Myzus ornatus, persicae; [Ovatomyzus chamaedrys];
	Ovatus crataegarius

Key to apterae on Origanum:-

1	ANT usually 4-segmented, 0.12-0.15 × BL, with PT/BASE less than 0.5. Eyes 3-facetted. SIPH absent. Legs very short, with fore- and mid-tarsi usually 1-segmented. Dorsal wax glands present on head, thorax and ABD TERG 1-8, comprising facets surrounding an elongate central area	…..Kaltenbachiella pallida
–	ANT 5- or 6-segmented, more than 0.5 × BL, with PT/BASE more than 1. Eyes multifacetted, SIPH present, tarsi 2-segmented and wax glands not evident	…..2
2	SIPH strongly swollen, 5.4-8.2 × cauda, with maximum diameter of swollen part more than 2 × minimum diameter of stem, smooth except for a little subapical polygonal reticulation	…..Eucarazzia elegans

–	SIPH not swollen or much less swollen, and less than 3.5 × cauda	…..3
3	Head smooth, ANT tubercles weakly developed. Marginal tubercles (MTu) present on ABD TERG 1 and 7	…..4
–	Head spiculose with well-developed ANT tubercles, their inner faces spiculose or scabrous and steep-sided. MTu absent from ABD TERG 1 and 7	…..7
4	SIPH pale with dark apices	…..Aphis nasturtii
–	SIPH wholly dark	…..5
5	Cauda with 11-24 hairs. Hairs on ANT III 0.8-3.4 × BD III	…..Aphis fabae
–	Cauda with 4-8 hairs. Hairs on ANT III 0.3-0.7 × BD III	…..6
6	SIPH 0.10-0.12 × BL, 1.05-1.45 × cauda. ABD TERG 7 and 8 usually with dark cross-bands	…..Aphis origani
–	SIPH 0.12-0.26 × BL, 1.3-2.5 × cauda. ABD TERG 7 and 8 rarely with dark cross-bands	…..Aphis gossypii

7	Dorsal abdomen without any dark markings	…..8
–	Dorsal abdomen with dark markings	…..10
8	SIPH slightly but distinctly swollen on distal half. ANT 0.7-1.0 × BL	…..Myzus persicae
–	SIPH tapering/cylindrical on distal half. ANT 1.1-1.5 × BL	…..9
9	Inner faces of ANT tubercles with convergent, rounded, scabrous processes. ANT III without rhinaria. ANT PT/BASE 5.2-7.6. R IV+V 1.3-1.6 × HT II, with 2-4 accessory hairs	…..Ovatus crataegarius

–	Inner faces of ANT tubercles without processes, approximately parallel. ANT III usually with 1-2 small rhinaria near base. ANT PT/BASE 4.0-5.4. R IV+V 1.1-1.4 × HT II, with 5-7 accessory hairs	…..Aulacorthum solani
10	Dorsal abdomen with a large, roughly U-shaped black patch. ANT PT/BASE 4.3-5.2	…..Neomyzus circumflexus
–	Dorsal abdomen with a pattern of dark intersegmental markings. ANT PT/BASE 1.7-2.8	…..Myzus ornatus

Orixa	Rutaceae
Orixa japonica	?Aulacorthum ?solani (as Myzus kusaki Shinji);
	Pseudomegoura magnoliae

Use key to polyphagous aphids.

Orlaya	Apiaceae
Orlaya grandiflora	Aphis solanella; Cavariella theobaldi; Dysaphis crataegi;
	Hyadaphis passerinii

Key to apterae on Orlaya:-

1	SIPH dark, clavate and about equal in length to the dark cauda	…..Hyadaphis passerinii
–	SIPH pale or dark, tapering/cylindrical, longer than cauda, which may also be pale or dark	…..2

2	ABD TERG 8 with a backwardly-pointed process bearing 2 hairs	…..Cavariella theobaldi
–	No process on ABD TERG 8	…..3
3	Cauda helmet-shaped, not longer than its basal width, usually with 5 hairs. Spinal tubercles (STu) present on head and ABD TERG 8 or, 7 and 8, and marginal tubercles (MTu) on ABD TERG 1-5, but not usually on 7	…..Dysaphis crataegi
–	Cauda tongue-shaped, longer than its basal width, with 11-23 hairs. STu absent, and MTu only regularly present on ABD TERG 1 and 7	…..Aphis fabae group (incl. solanella)

Ormenis see Chamaemelum

Asteraceae

Ornithidium	Orchidaceae
Ornithidium adendrobium	Cerataphis orchidearum

Ornithogalum	Asparagaceae
Ornithogalum dubium	Aphis gossypii
Ornithogalum spp.	Myzus persicae; Rhopalosiphum nymphaeae, padi

Key to apterae on Ornithogalum:-

–	Dorsal cuticle with a pattern of spinules arranged in polygons, with 1-3 spicules in the centre of each polygon. SIPH clavate	…..Rhopalosiphum nymphaeae
–	Without the above combination of characters; if dorsal cuticle has a pattern of spinules arranged in polygons then SIPH not clavate	…..go to key to polyphagous aphids

Ornithopus	Fabaceae
Ornithopus compressus	Aphis craccivora
O. isthmocarpus = O. sativus ssp. isthmocarpus
O. perpusillus	Acyrthosiphon pisum; Aphis craccivora
O. sativus (incl. ssp. isthmocarpus)	Aphis craccivora

Key to apterae on Ornithopus:-

–	Body oval, with an extensive black sclerotic dorsal shield, BL 1.4-2.2 mm. SIPH and cauda black	…..Aphis craccivora
–	Body spindle-shaped, pale, BL 2.5-4.4 mm. SIPH and cauda pale. (Additional check – ANT VI BASE 0.25-0.4 mm, 1.8-2.3 × R IV+V – otherwise go to key to polyphagous aphids)	…..Acyrthosiphon pisum

Orobanche (including Aphyllon)	Orobanchaceae
Orobanche aegyptiaca	Aphis gossypii, [Aphis sp. (Davletshina 1964)];
	Rectinasus buxtoni; Smynthurodes betae
O. foetida	[Geoica utricularia]
O. crenata	Smynthurodes betae
O. hederae	Macrosiphum euphorbiae
O. lutea	[Aphis orobanches]
O. mutelii	[Aphis orobanches]
O. ramosa	[Aphis orobanches]; [Dysaphis candicans];
	[Brachycaudus cardui (? – as Aphis phelipaeae Passerini)];
	Smynthurodes betae
O. variegata	Smynthurodes betae
Orobanche sp.	[Anuraphis subterranea]; Protaphis middletonii;
	[Siphonophora orobanches Lichtenstein (nomen nudum)];
	Myzus persicae; Rhopalosiphum rufiabdominale;
	Trama orobanches

Key to apterae on Orobanche:-

[Only the original descriptions of Aphis orobanches and Dysaphis candicans are available (Passerini 1879), and are insufficient to include these species in the key; see text under these names for further information.]

1	ANT 5-segmented, with ANT V BASE very long, more than 15 × longer than the short	peg-like PT. R IV+V extremely long, similar in length to hind femur …..Rectinasus buxtoni
–	ANT 5- or 6-segmented, base of last segment and R IV+V relatively much shorter	…..2
2	HT II greatly elongated, more than 0.5 × hind tibia	…..Trama orobanches
–	HT II of normal length	…..3
3	Thoracic spiracles greatly enlarged, rounded, much larger than abdominal spiracles. ANT PT/BASE 7.0-11.4, usually more than 8.0. ANT III with 14-36 rhinaria	…..Nasonovia ribisnigri

–

Thoracic spiracles similar in size to abdominal ones. ANT PT/BASE less than 6. ANT III with 0-10 rhinaria

…..go to key to polyphagous aphids

Orostachys	Crassulaceae
Orostachys spinosa	Aphis sedi

Ortantha see Odontites

Orobanchaceae

Orthilia (including Ramischia)	Ericaceae
Orthilia secunda	Aulacorthum pirolacearum

Orthocarpus	Orobanchaceae
Orthocarpus luteus	Nasonovia alpina
O. purpurascens	Macrosiphum orthocarpus
(= Castelleja exserta)

Key to apterae on Orthocarpus:-

–	BL 1.9-2.5 mm. ANT III-V dark only at apices, and SIPH pale or uniformly pigmented, without subapical polygonal reticulation. (Also check: thoracic spiracular apertures much larger than abdominal ones, which are almost covered by cowl-like opercula. R IV+V 1.6-2.1 × HT II with 12-18 accessory hairs)	…..Nasonovia alpina
–	BL more than 3 mm. ANT black beyond basal part of III. SIPH black on distal c.0.7 (and with subapical reticulation?)	…..Macrosiphum orthocarpus*

Orthostemon = Acca

Myrtaceae

Oryza	Poaceae
Oryza sativa	Anoecia corni, fulviabdominalis; Aphis gossypii;
	Brachysiphoniella montana; Chaetogeoica polychaeta;
	Diuraphis noxia; Forda orientalis;
	Geoica lucifuga, setulosa, utricularia;
	Hyalopterus amygdali; Hysteroneura setariae;
	Melanaphis sacchari; Metopolophium dirhodum;
	Paracletus cimiciformis; [Prociphilus sp.];
	Rhopalosiphum maidis, nymphaeae, padi, rufiabdominale, rufulum;
	Schizaphis graminum; Sipha flava, glyceriae, maydis;
	Sitobion akebiae, avenae, graminis, miscanthi;
	Tetraneura akinire, basui, javensis, nigriabdominalis, radicicola, ulmi

Use key to apterae of grass-feeding aphids under Digitaria, or for a simple key to common aphids on rice see Blackman & Eastop 2000.

Oryzopsis (including Eriocoma, Piptantherum)	Poaceae
Oryzopsis cuspidata = O. hymenoides
O. hymenoides	Forda marginata
O. lateralis	Sitobion himalayensis
O. miliacea	Melanaphis sacchari; Myzus persicae; Sitobion avenae

Use key to apterae of grass-feeding aphids under Digitaria.

Osbeckia	Melastomataceae
Osbeckia capitata	Aphis gossypii, nasturtii; [Capitophorus carduinus];
	Myzus ornatus, persicae
O. chinensis	Aphis nasturtii; Brachycaudus helichrysi;
	[Rhopalosiphum rufiabdominale]
O. crinata	Aphis aurantii, gossypii; [Capitophorus sp.];
	Myzus persicae

Use key to polyphagous aphids.

Osmanthus	Oleaceae
Osmanthus aquifolius	Prociphilus osmanthae
O. asiaticus	[Shivaphis hangzhouensis]
O. aurantiacus	Prociphilus osmanthae
O. aurantiacus var. thunbergii	Pseudomegoura magnoliae
O. × burkwoodii	Prociphilus osmanthae
O. heterophyllus	Prociphilus osmanthae
O. insularis	Aphis odinae
–	SIPH absent. ANT PT/BASE less than 1	…..Prociphilus osmanthae
–	SIPH present. ANT PT/BASE more than 1	…..go to key to polyphagous aphids

Osmaronia see Oemleria

Rosaceae

Osmia see Eupatorium

Asteraceae

Osmorhiza	Apiaceae
Osmorhiza aristata (incl. var. longistylis)	Aphis fabae; Cavariella aegopodii, theobaldi;
	Semiaphis heraclei; [Uroleucon parvotuberculatum]
O. chilensis	Macrosiphum euphorbiae; Myzus ascalonicus;
	[Rhopalosiphoninus staphyleae]
O. claytoni = O. aristata
O. longistylis see aristata
Osmorhiza sp.	Aphis asclepiadis

Use key to apterae on Apium.

Osmunda	Osmundaceae
O. cinnamomea	Amphorophora ampullata ssp. laingi
O. japonica	Amphorophora ampullata; Aulacorthum solani;
	Taiwanomyzus babai, filicis
O. regalis	Aulacorthum solani; Macrosiphum walkeri;
	Micromyzella pterisoides; Neomyzus circumflexus
Osmunda sp.	Macrosiphum euphorbiae

Use key to apterae on ferns under Polypodium.

Osmundastrum	Osmundaceae
Osmundastrum asiaticum	Micromyzus nikkoensis, osmundae
O. claytonianum	Micromyzus osmundae

Use key to apterae on ferns under Polypodium.

Osteomeles	Rosaceae
Osteomeles schwerinae	Myzus persicae
O. subrotunda	Aphis gossypii

Use key to polyphagous aphids.

Osteospermum	Asteraceae
Osteospermum ecklonis	Macrosiphum euphorbiae; Uroleucon compositae
O. moniliferum = Chrysanthemoides monilifera
O. spinescens	Aphis craccivora
O. vaillantii = Tripteris vaillantii

Use key to polyphagous aphids.

Ostericum	Apiaceae
Ostericum melanotilingia = Angelica decursiva

Ostrya	Hop-hornbeams Corylaceae
Ostrya carpinifolia	Pterocallis ostryae
O. japonica	Mesocallis pteleae
O. virginiana	Macrosiphum (Neocorylobium) pseudocoryli

Key to aphids on Ostrya:-

1	SIPH long, tubular, dark, with subapical zone of polygonal reticulation. Cauda long and tongue-shaped, anal plate entire. ANT PT/BASE more than 5	…..Macrosiphum (Neocorylobium) pseudocoryli
–	SIPH as short, truncated cones. Cauda knobbed, anal plate bilobed. ANT PT/BASE 1.2 or less	…..2
2	ANT III of alata dark, with 7-14 secondary rhinaria. ANT PT/BASE 0.9-1.2	…..Mesocallis pteleae
–	ANT III of alata pale with 4-7 secondary rhinaria. ANT PT/BASE 0.3-0.6	…..Pterocallis ostryae

Ostryoderris = Aganope

Fabaceae

Ostryopsis	Betulaceae
Ostryopsis davidiana	Corylobium avellanae

Othonna (including Hertia, Othonnopsis)	Asteraceae
Othonna cheirifolia	Macrosiphum euphorbiae

Othonnopsis see Othonna

Asteraceae

Otites see Silene

Caryophyllaceae

Otochilus	Orchidaceae
Otochilus porrectus	Sitobion indicum, luteum

Use key to apterae on orchids under Cymbidium.

Ottelia	Hydrocharitaceae
Ottelia alismoidis	Rhopalosiphum nymphaeae

Ourisia	Plantaginaceae
Ourisia microphylla	Neomyzus circumflexus

Ourouparia see Uncaria

Rubiaceae

Oxalis	Oxalidaceae
Oxalis acetosella	Aphis nasturtii; Aulacorthum solani;
	[Hyperomyzus lactucae]; [Jacksonia papillata];
	[Metopolophium frisicum]; Myzus ascalonicus, persicae;
	Rhopalosiphoninus staphyleae
O. articulata	Myzus ornatus; Neomyzus circumflexus
O. cernua = O. pes-caprae
O. corniculata	Aphis aurantii, craccivora, gossypii, nasturtii, spiraecola;
	Aulacorthum solani; Brachycaudus helichrysi;
	Macrosiphum euphorbiae;
	Myzus cymbalariae, ornatus, persicae;
	Indomasonaphis anaphalidis; Neomyzus circumflexus;
	Neotoxoptera oliveri;
	Rhopalosiphoninus latysiphon, staphyleae
O. debilis var. corymbosa	Aphis fabae; Myzus persicae
O. deppei	Aphis fabae; Neomyzus circumflexus
O. enneaphylla	Myzus ascalonicus
O. latifolia	Aphis gossypii; Macrosiphum euphorbiae;
	[Micromyzodium filicium]; Myzus persicae
O. laxa	Myzus cymbalariae
O. martiana = O. debilis var. corymbosa
O. oregana	Macrosiphum sp. (Oregon, USA; BMNH collection, leg. D. Hille Ris Lambers);
	Rhopalosiphoninus staphyleae
O. pes-caprae	Aphis aurantii, craccivora, fabae, gossypii, solanella,
	spiraecola;
	Aulacorthum solani;
	Macrosiphum euphorbiae; Myzus persicae;
	Rhopalosiphoninus staphyleae
O. purpurea	Myzus persicae
O. rosea	Myzus persicae; Neomyzus circumflexus
O. semiloba	Aphis gossypii; Myzus persicae
O. stricta	Abstrusomyzus reticulatus; Protaphis middletonii
O. trilliifolia	Myzus ornatus, persicae
O. variabilis = O. purpurea
O. versicolor	Aphis fabae
O. violacea = O. debilis var. corymbosa
Oxalis sp.	[Rhopalosiphum maidis]

Key to apterae on Oxalis:-

1	BL 3.8-4.7 mm. SIPH pale, smooth and markedly swollen on distal 0.7 (Fig.34a). Dorsal hairs long, thick, and blunt or slightly expanded apically	…..Indomasonaphis anaphalidis
–	Without that combination of characters	…..2
2	Dorsum with an extensive solid dark sclerotic shield, with very conspicuous, dark, non-spinulose reticulation. SIPH slightly swollen near apex	…..Abstrusomyzus reticulatus
–	Dorsum with or without dark markings; if with a solid dark sclerotic dorsal shield then this either lacks reticulation, or the reticulation is either pale or finely spinulose, and SIPH are either markedly inflated over more than half of length or completely lack any trace of swelling	…..3
3	SIPH cylindrical/tapering, with polygonal reticulation on distal 0.12-0.26 of length	…..4
–	SIPH if cylindrical/tapering then without polygonal reticulation	…..go to key to polyphagous aphids

4	ABD TERG 7 and 8 mostly with spinal tubercles (STu) and ABD TERG 2-5 often with marginal tubercles (MTu)	…..Macrosiphum sp. (Oregon, BMNH collection)
–	Stu and MTu only sporadically present	…..Macrosiphum euphorbiae

Oxybaphus	Nyctaginaceae
Oxybaphus angustifolius = Mirabilis nyctaginea var. angustifolia
O. nyctagineus	Aphis asclepiadis, fabae; Macrosiphum euphorbiae

Use key to polyphagous aphids.

Oxycoccus see Vaccinium	Ericaceae

Oxydendrum	Ericaceae
Oxydendrum arboreum	Aulacorthum solani

Oxylobium	Fabaceae
Oxylobium callistachys	Aphis gossypii
O. lineare	Aphis gossypii

Oxylobus	Asteraceae
Oxylobus sp.	Aphis solitaria

Oxypetalum	Apocynaceae
Oxypetalum sp.	Aphis gossypii, nerii

Use key to polyphagous aphids.

Oxypogon see Lathyrus

Fabaceae

Oxyria	Polygonaceae
Oxyria digyna	Aphis fabae; Indomasonaphis rumicis;
	Nasonovia ribisnigri

Key to apterae on Oxyria:-

1	BL more than 3.5 mm. SIPH pale and strongly swollen on distal part	…..Indomasonaphis rumicis*
–	BL less than 3 mm. SIPH pale or dark, and tapering or cylindrical on distal part	…..2
2	ANT tubercles well-developed. ANT PT/BASE 7.0-11.4. Thoracic spiracles much larger than abdominal ones, with apertures rounded	…..Nasonovia ribisnigri
–	ANT tubercles weakly developed. ANT PT/BASE 1.7-3.5. Thoracic spiracles similar in size to abdominal ones, with apertures reniform	…..Aphis fabae

Oxytropis	Fabaceae
Oxytropis campestris	Acyrthosiphon churchillense; Aphis astragali;
	Nearctaphis vera
O. deflexa (incl. var. sericea)	Acyrthosiphon churchillense
O. glabra	Megoura viciae (ssp. turanica Nevsky 1929)
O. hudsonica = viscida var. hudsonica
O. lambertii	Aphis ?craccivora (as medicaginis)
O. microphylla	Aphis craccivora
O. myriophylla	Aphis craccivora
O. oxyphylla	Aphis craccae, oxytropis
O. pilosa	Aphis craccivora; Acyrthosiphon pisum
O. sordida	Aphis astragali; Nearctaphis vera
O. viscida var. hudsonica	Acyrthosiphon churchillense; Aphis masoni
Oxytropis spp.	Acyrthosiphon kondoi; Aphis oxytropiradicis, [polaris]

Key to apterae on Oxytropis:-

1	(Only al. known, but the following should also apply to apt.) Cauda as short as or shorter than its basal width in dorsal view. SIPH with transverse rows of spinules. Longest hairs on ANT III 60-70 μm, c.2.5 × BD III	…..Nearctaphis vera*
–	Cauda tongue- or finger-shaped, longer than its basal width. SIPH with normal imbrication. Longest hairs on ANT III 0.3-2.2 × BD III	…..2
2	ANT tubercles well developed, with smooth divergent inner faces. ABD TERG 1 and 7 without marginal tubercles (MTu). (SIPH without subapical reticulation)	…..3
–	ANT tubercles undeveloped or weakly developed. ABD TERG 1 and 7 with MTu	…..6
3	SIPH black, black, swollen in middle (cigar-shaped), similar in length to cauda, which is also black	…..Megoura viciae
–	SIPH mainly pale, tapering/cylindrical, longer than cauda, which is also pale	…..4
4	SIPH very attenuate distally, thinner than hind tibiae at their respective midlengths. ANT BASE VI 1.9-2.9 × R IV+V	…..Acyrthosiphon pisum
–	SIPH gradually tapering, not attenuate distally, thicker than hind tibia at their respective midlengths. ANT BASE VI 1.1-1.8 × R IV+V	…..5
5	ANT III with (2-) 4-11 rhinaria in a row on basal half. SIPH 1.2-1.6 × cauda	…..Acyrthosiphon churchillense

–	ANT III with 1 (-3) rhinaria near base. SIPH 1.6-2.1 × cauda	…..Acyrthosiphon kondoi
6	Dorsal abdomen without any sclerotisation. Large MTu consistently present on ABD TERG 2-4 as well as 1 and 7. R IV+V c. 1.5 × HT II	…..Aphis oxytropiradicis*
–	Dorsal abdomen with at least some sclerotisation. MTu absent from ABD TERG 2-4 or only sporadically present, and small. R IV+V less than 1.4 × HT II	…..7
7	Hairs on ANT III 0.3-0.75 × BD III. Dorsal abdomen usually with a solid black shield extending over all of ABD TERG 1-6. SIPH 1.2-2.2 × cauda, which bears 4-9 hairs	..…Aphis craccivora

–	Hairs on ANT III 0.8-2.2 × BD III. Dorsal abdomen with scattered or segmentally-divided black markings, or with a variably developed or fragmented black shield that does not usually extend laterally to unite with marginal sclerites on ABD TERG 1-3. SIPH 0.5-1.1 × cauda, which bears 6-16 hairs	…..8
8	R IV+V markedly narrowed subapically, with acute apex; 1.2-1.3 × HT II	…..Aphis oxytropis*

–	R IV+V tapering gradually to blunt apex; 0.8-1.1 × HT II	…..9
9	Dorsal abdomen with solid black shield extending over middle parts of ABD TERG 1-3 or 1-4 and completely across ABD TERG 4-6 or 5-6. ANT PT/BASE (1.7-)1.9-2.4	…..Aphis craccae
–	Dorsal abdominal sclerotisation variable but all tergites with at least some intersegmental division. ANT PT/BASE 1.3-1.9 (-2.0)	…..10
10	SIPH 0.50-0.65 (-0.67) × cauda	…..Aphis masoni
–	SIPH (0.65-) 0.70-1.1 × cauda	…..11
11	Dorsal abdomen with spino-pleural bars on ABD TERG 4-6 or 5-6, but ABD TERG 1-2 (-3) only ever with scattered small sclerites (Fig.16i). Cauda tongue-shaped, 0.23-0.33 mm	…..Aphis astragali

–

Dorsal abdomen variably but more evenly sclerotised. Cauda elongate triangular, 0.16-0.21 mm

…..Aphis polaris

Ozoroa	Anacardiaceae
Ozoroa insignis	Aphis gossypii
O. paniculosa	Aphis gossypii

Ozothamnus	Asteraceae
Ozothamnus diosmifolius	Myzus persicae
O. leptophyllus	[?Casimira sp. (New Zealand; see Teulon et al. 2013)]

P

Pachira	Malvaceae
Pachira spp.	Aphis craccivora, gossypii; Protaphis middletonii

Use key to polyphagous aphids.

Pachylophis	Onagraceae
Pachylophis cespitosa	Aphis oenotherae

Pachycarpus	Apocynaceae
Pachycarpus lineolatus	Aphis nerii
P. schinzianus	Aphis nerii

Pachypleurum	Apiaceae
Pachypleurum alpinum	Cavariella nipponica

Pachystachys	Acanthaceae
Pachystachys lutea	Aphis aurantii, gossypii; Myzus persicae

Use key to polyphagous aphids.

Pachystima	Celastraceae
Pachystima myrsinites	Wahlgreniella sp. (western USA; A. Jensen, aphidtrek.org)

Packera see Senecio	Asteraceae
P. anonyma see Senecio anonymus
P. aurea see Senecio aureus
P. cana see Senecio canus
P. glabella see Senecio glabellus
P. paupercula see Senecio pauperculus
P. plattensis see Senecio plattensis
P. tomentosa see Senecio tomentosus

Padus see Prunus	Rosaceae
Padus avium see Prunus padus

Paederia	Rubiaceae
Paederia chinensis = P. foetida
P. foetida (incl. chinensis, mairei, maritima, scandens, tomentosa)	Aphis gossypii, spiraecola;
	Aulacorthum esakii, [myriopteroni];
	Pseudomegoura nipponica
P. scandens = P. foetida
P. tomentosa = P. foetida

Key to apterae on Paederia:-

1	Head dark and densely spiculose at least on ventral surface, with ANT tubercles well-developed and steep-sided	…..2
–	Without that combination of characters	…..go to key to polyphagous aphids
2	Tergum wholly dark sclerotic. SIPH cylindrical/tapering on distal half, mainly pale/dusky, sometimes darker at base and apex. Longest hairs on ANT III more than 0.5 × BD III	…..Aulacorthum esakii

–

Tergum not wholly sclerotic, often with variably developed dark sclerites on ABD TERG 1-6. SIPH somewhat swollen on distal half, and wholly dark. Longest hairs on ANT III less than 0.5 × BD III

…..Pseudomegoura nipponica

Paeonia	Paeoniaceae
Paeonia lactiflora	Myzus persicae
P. ×suffruticosa	Aphis gossypii, spiraecola

Use key to polyphagous aphids.

Palaquium	Sapotaceae
Palaquium sp.	Parathoracaphis setigera

Palicourea	Rubiaceae
Palicourea alpina	Aphis (Toxoptera) aurantii; Aulacorthum solani

Use key to polyphagous aphids.

Palisota	Commelinaceae
Palisota ambigua	Pentalonia nigronervosa
P. hirsuta	Pentalonia nigronervosa
P. thyrsiflora = P. ambigua

Paliurus	Rhamnaceae
Paliurus spina-cristi	Aphis frangulae, gossypii, [paliuri Lichtenstein (nomen nudum)], nasturtii, Aphis sp. (Toros et al., 2002: 31)
Paliurus sp.	[Aphis exploratus (= nasturtii?)]

Use key to aphids on Rhamnus.

Pallenis	Asteraceae
Pallenis maritima	Brachycaudus helichrysi; Protaphis terricola
P. spinosa = Asteriscus spinosus

Use key to apterae on Asteriscus.

Palura see Symplocos	Symplocaceae
Palura chinensis = Symplocos paniculata

Panax	Araliaceae
Panax spp.	Aphis aurantii, craccivora, odinae; Myzus persicae;
	[Rhopalosiphoninus latysiphon]

Use key to polyphagous aphids.

Pandanus	Pandanaceae
Pandanus tectorius	Astegopteryx pandani

Pandiaka	Amaranthaceae
Pandiaka involucrata	Aphis gossypii

Pandorea	Bignoniaceae
Pandorea pandorana	Myzus ornatus
P. ricasoliana	Aphis gossypii

Use key to polyphagous aphids.

Panicularia see Glyceria

Poaceae

Panicum	Poaceae
Panicum adenophorum	Sitobion neusi, [Sitobion sp. (Millar 1994)]
P. afzelii	Aphis gossypii
P. antidotale	Anoecia corni, furcata;
	[Colopha ulmicola? (as Rhizobius spicatus)];
	Hysteroneura setariae; Rhopalosiphum maidis
P. barbinode = Brachiaria mutica
P. boliviense = Polygonum polygonatum
P. capillare	Anoecia corni, cornicola; Geoica setulosa;
	Hysteroneura setariae; Protaphis middletonii;
	Rhopalosiphum maidis
P. clandestinum	Hysteroneura setariae
P. colonum = Echinochloa colonum
P. coloratum	Rhopalosiphum maidis; [Sitobion sp. (Millar 1994)]
P. conjugatum = Paspalum conjugatum
P. crus-corvi = Echinochloa crus-galli
P. crusgalli = Echinochloa crus-galli
P. decompositum	Hysteroneura setariae
P. deustum	Rhopalosiphum maidis
P. dichotomiflorum	Anoecia corni; Rhopalosiphum maidis
P. fasciculatum = Brachiaria fasciculata
P. fimbriatum = Digitaria ciliaris
P. flavidum = Paspalidium flavidum
P. germanicum = Setaria italica
P. glabrum = Digitaria ischaemum
P. glanduliferum	Sitobion neusi
P. glutinosum	Hysteroneura setariae; Rhopalosiphum padi
P. hemitomum	Rhopalosiphum maidis
P. hirticaule	Tetraneura akinire
P. infestum	Rhopalosiphum maidis
P. javanicum = Urochloa panicoides
P. laevifolium = Panicum schinzii
P. laxum	Hysteroneura setariae
P. maximum	Hysteroneura setariae; Rhopalosiphum maidis;
	Sipha flava;
	Sitobion africanum, lambersi, [Sitobion sp. (Millar 1994)];
	Tetraneura akinire
P. miliaceum	Anoecia corni, vagans; [Diuraphis muehlei];
	Forda marginata; Geoica utricularia;
	Hysteroneura setariae; Melanaphis pyraria, sacchari;
	Myzus persicae; Neomyzus circumflexus;
	Paracletus cimiciformis, cimiciformis ssp. panicumi;
	[Prociphilus bumeliae];
	Rhopalosiphum maidis, nymphaeae, padi;
	Schizaphis graminum; Sipha maydis; Sitobion avenae;
	Tetraneura akinire, caerulescens, javensis, ulmi, yezoensis
P. montanum = Panicum notatum
P. muticum = Brachiaria mutica
P. notatum	Hysteroneura setariae
P. novemnerve	Tetraneura akinire
P. paludosum	Brachysiphoniella montana
P. patens = Cyrtococcum patens
P. pilosum	Tetraneura akinire
P. plicatum = Setaria palmifolia
P. polycaulon = Panicum strigosum
P. polygonatum	Aphis gossypii; Hysteroneura setariae
P. proliferum = P. antidotale
P. prostratum = Brachiaria reptans
P. psilopodium = P. sumatrense
P. purpurascens = Brachiaria mutica
P. repens	Brachysiphoniella montana; Hysteroneura setariae;
	Schizaphis hypersiphonata; Sitobion avenae, fragariae
P. reptans = Brachiaria reptans
P. sanguinale = Digitaria sanguinalis
P. schinzii	Sitobion ?africanum
P. scoparium	Hysteroneura setariae; Tetraneura akinire
P. sellowii	Tetraneura akinire
P. strigosum	Hysteroneura setariae; Tetraneura akinire
P. sumatrense	Hysteroneura setariae
P. teneriffae = Tricholaena teneriffae
P. trichoides	Pseudoregma panicola
P. trigonum = Cyrtococcum trigonum
P. turgidum	Forda
P. virgatum	Anoecia cornicola; Rhopalosiphum maidis
Panicum spp.	Aphis craccivora, Aphis (Toxoptera) aurantii;
	Anoecia fulviabdominalis;
	Ceratovacuna graminum, panici; Colopha ulmicola;
	Diuraphis noxia; Geoica utricularia;
	[Kaltenbachiella nirecola]; Laingia psammae;
	Prociphilus erigeronensis;
	Sitobion miscanthi; Tetraneura ulmi

Use key to apterae of grass-feeding aphids under Digitaria.

Panzeria see Panzerina	Lamiaceae

Panzerina (including Panzeria)	Lamiaceae
Panzerina lanata	Aphis panzeriae

Papaver	Papaveraceae
Papaver alpinum	Aulacorthum solani; Rhopalosiphoninus staphyleae
P. arenarium	Aphis fabae
P. argemone	Aphis solanella; Myzus ascalonicus
P. canescens	Acyrthosiphon ilka
P. croceum = P. nudicaule
P. decaisnei	Acyrthosiphon ilka
P. dubium	Aphis fabae; Brachycaudus helichrysi; Myzus persicae
P. glaucum	[Lipaphis pseudobrassicae]; Myzus persicae
P. hybridum	Aphis craccivora, fabae, solanella
P. laestadianum	Aphis fabae
P. macrostomum	Aphis fabae
P. nudicaule	Acyrthosiphon ilka, [ilka ssp. montanum];
	Aphis craccivora; Macrosiphum euphorbiae;
	Myzus persicae; Neomyzus circumflexus
P. orientale	Aphis fabae; Aulacorthum solani; Brachycaudus helichrysi;
	Macrosiphum euphorbiae, [gei]; Neomyzus circumflexus
P. pavoninum	Acyrthosiphon ilka; Aphis craccivora, fabae
P. pilosum (including ssp. strictum)	Aphis fabae, kazdagensis; Brachycaudus cardui
P. pinnatifidum	Aphis fabae
P. rhoeas	Aphis fabae, gossypii, solanella; Aulacorthum solani;
	Macrosiphum euphorbiae; Myzus persicae
P. somniferum	Acyrthosiphon ilka, [papaverinum], papaverisuctum,
	[titovi Mordvilko (nomen nudum)];
	Aphis fabae, gossypii, [idaei], nasturtii, solanella, [triglochinis];
	Brachycaudus helichrysi; [Lipaphis pseudobrassicae];
	Macrosiphum euphorbiae, [stellariae];
	Myzus ascalonicus, persicae; Rectinasus buxtoni
	Rhopalosiphum padi; Smynthurodes betae
P. strigosum = P. rhoeas
P. subpiriforme	Macrosiphum euphorbiae
P. tianschanicum = P. canescens
Papaver spp.	[Macrosiphum stellariae]; Rhopalosiphum rufiabdominale

Key to apterae on Papaver:-

1	ANT PT/BASE less than 0.3. Body and appendages densely hairy. SIPH absent	…..2
–	ANT PT/BASE at least 0.5. Body and appendages not densely hairy. SIPH present	…..3
2	ANT V BASE and R IV+V both very long, respectively about 1.7 and 2.5 × width of head between antennal bases. ANT II similar in length to ANT I, much shorter than III	.….Rectinasus buxtoni
–	ANT V BASE and R IV+V of normal length , both about 0.5 × width of head between antennal bases. ANT II about twice as long as ANT I, similar in length to III	..…Smynthurodes betae

3	SIPH pale, long, tapering or cylindrical on distal half, and without subapical polygonal reticulation. ANT tubercles with smooth, broadly divergent inner faces, and median frontal tubercle evident	…..4
–	SIPH either not pale, long and tapering, or with subapical polygonal reticulation, and other characters not in above combination	…..5
4	SIPH 1.67-2.2 × cauda. R IV+V 0.75-0.95 × HT II	…..Acyrthosiphon ilka
–	SIPH 1.4-1.5 × cauda. R IV+V 0.69-0.77 × HT II	…..Acyrthosiphon papaverisuctum
5	URS with 5-6 accessory setae, ABD TERG IV and 5 each with a pair of spinopleural sclerites.	…..Aphis kazdagensis
–
6	Cauda helmet-shaped, somewhat constricted at base, not longer than its basal width in dorsal view. SIPH with a subapical annular incision. Spiracular apertures large and rounded	…..7

–	Cauda not helmet-shaped. SIPH without a subapical annular incision. Spiracular apertures small, usually reniform	…..go to key to polyphagous aphids
	(but note that specimens running to Macrosiphum euphorbiae could be M. stellariae)
7	Dorsal abdomen with an extensive solid black shield. ANT III 0.31-0.47 mm, 2.4-3.4 × HT II. R IV+V 0.17-0.24 mm. SIPH dark, imbricated, 1.7-3.4 × cauda	……Brachycaudus cardui

–

Dorsal abdomen without a black shield. ANT III 0.07-0.25 mm, 0.9-2.2 × HT II. R IV+V 0.10-0.15 mm. SIPH pale, smooth, 0.8-2.0 × cauda

……Brachycaudus helichrysi

Paphiopedilum	Orchidaceae
Paphiopedilum insigne	Neomyzus circumflexus; Sitobion indicum/luteum group
P. venustum	Aulacorthum solani
Paphiopedilum spp.	Cerataphis orchidearum; [Pentalonia nigronervosa]

Use key to aphids on orchids under Cymbidium.

Pappea	Sapindaceae
Pappea capensis	Aphis aurantii, citricidus, gossypii

Use key to polyphagous aphids.

Pappobolus	Asteraceae
Pappobolus microphyllus	Uroleucon helianthicola, pseudambrosiae

Use key to apterae on Helianthus.

Parabenzoin see Lindera

Lauraceae

Parageum see Geum	Rosaceae
P. montanum see Geum montanum

Parahebe	Plantaginaceae
Parahebe catarractae	Myzus ornatus

Paraixeris	Asteraceae
Paraixeris denticulata	Aphis gossypii (? – on roots with eggs; Chu 1949);
	Hyperomyzus carduellinus; Uroleucon formosanum

Use key to apterae on Ixeris.

Parasenecio	Asteraceae
Parasenecio auriculatus	Aphis fabae; Uroleucon gobonis
P. delphiniifolia	Brachycaudus helichrysi
P. hastatus (incl. ssp. orientalis)	Aphis fabae, gossypii, [grossmannae], jacobaeae, spiraecola;
	Aulacorthum solani; Brachycaudus helichrysi;
	Uroleucon fuchuense
Parasenecio sp.	Aleurodaphis mikaniae

Key to apterae on Parasenecio :-

1	Body elongate oval, sclerotic dorsally, with a crenulate margin due to a continuous fringe of wax glands. SIPH as pores with raised rims. Cauda knobbed, anal plate bilobed	…..Aleurodaphis mikaniae
–	Body oval or spindle-shaped, without a marginal fringe of wax glands. SIPH tubular. Cauda tongue- or finger-shaped, anal plate entire	…..2
2	SIPH dark with polygonal reticulation on distal 0.23-0.33 of length. Cauda pale. Hind tibia with a ventral row of short peg-like hairs. Dorsal abdominal hairs long and fine-pointed (longest more than 90 μm)	..…Uroleucon fuchuense
–	Without that combination of characters	…..3
3	Abdomen with large marginal tubercles (MTu) placed on dark marginal sclerites on ABD TERG 1-4(-6) and 7. Antennae, legs, SIPH and cauda all almost entirely dark	…..Aphis jacobaeae
–	MTu absent, small or only consistently present on ABD TERG 1 and 7. Appendages variously pigmented	…..go to key to polyphagous aphids
	(but note that specimens running to Uroleucon compositae may be U. gobonis).

Parathelypteris	Thelypteridaceae
Parathelypteris glanduligera	Macromyzus maculata; Micromyzodium polypodii
P. nipponica	Macromyzus maculata

Paratropia see Schefflera

Araliaceae

Pardanthopsis see Iris	Iridaceae
Pardanthopsis dichotoma = Iris dichotoma

Parentucellia	Orobanchaceae
Parentucellia latifolia	Brachycaudus mimeuri (?), persicae; [Myzus persicae]
P. viscosa	Brachycaudus helichrysi, persicae

Key to apterae on Parentucellia:-

(All three species have a short, helmet-shaped cauda, somewhat constricted at base.)

–	Dorsal abdomen usually with an extensive solid black shield. Femora dark except basally. SIPH dark, 2.2-3.4 × cauda	…..Brachycaudus persicae (or mimeuri? – see text)
–	Dorsal abdomen without a black shield. Femora mainly pale. SIPH pale, 0.8-2.0 × cauda	……Brachycaudus helichrysi

Parietaria	Urticaceae
Parietaria arborea = Gesnouinia arborea
P. debilis	Myzus fataunae
P. diffusa = P. judaica
P. floridana	Aphis gossypii
P. judaica	Aphis craccivora, fabae, gossypii, parietariae
P. lusitanica	Aphis parietariae
P. micrantha = P. debilis
P. officinalis	Aphis gossypii, parietariae
P. punctata	Aphis parietariae
P. ramiflora = P. judaica
Parietaria spp.	Myzus persicae

Key to apterae on Parietaria:-

1	ANT tubercles well developed, with inner faces parallel or convergent and strongly nodulose or spiculose. SIPH pale. ABD TERG 1 and 7 without marginal tubercles (MTu)	…..2
–	ANT tubercles weakly developed, cuticle of head not nodulose or spiculose. SIPH dark. ABD TERG 1 and 7 with MTu	…..3
2	ANT 5-segmented, with PT/BASE less than 2.5. ABD TERG 7 extended posteriorly, cowl-like	…..Myzus fataunae
–	ANT 6-segmented, with PT/BASE more than 2.8. ABD TERG 7 not extended posteriorly	…..Myzus persicae

3	Cauda with 11-24 hairs. Longest hairs on ANT III 0.8-2.2 × BD III	…..Aphis fabae
–	Cauda with 4-10 hairs. Longest hairs on ANT III 0.3-0.8 × BD III	…..4
4	Dorsal abdomen with an extensive black sclerotic shield	…..Aphis craccivora
–	Dorsal abdomen without dark markings	…..5
5	SIPH 1.0-1.5 × cauda, which bears 6-10 hairs. R IV+V 1.36-1.63 × HT II	…..Aphis parietariae
–	SIPH 1.3-2.5 × cauda, which bears 4-8 hairs. R IV+V 1.1-1.4 (-1.5) × HT II	…..Aphis gossypii

Parinari	Chrysobalanaceae
Parinari curatellifolia	Aphis gossypii

Parkia	Fabaceae
Parkia roxburghii = P. timoriana
P. timoriana	Aphis odinae

Parkinsonia	Fabaceae
Parkinsonia aculeata	Aphis craccivora

Parmena see Rubus	Rosaceae
Parmena spectabilis see Rubus spectabilis

Parmentiera	Bignoniaceae
Parmentiera aculeata	Aphis (Toxoptera) aurantii
P. edulis = P. aculeata

Parodichloa see Poa

Poaceae

Paronychia	Caryophyllaceae
Paronychia argentea	Aphis craccivora

Parrotia	Hamamelidaceae
Parrotia persica	Aphis gossypii

Parsonsia	Apocynaceae
Parsonsia heterophylla	Paradoxaphis plagianthi

Parthenium	Asteraceae
Parthenium argentatum	Rhopalosiphum rufiabdominale;
	Uroleucon ambrosiae ssp. lizerianum
P. bipinnatifidum	Uroleucon ambrosiae
P. hysterophorus	Acyrthosiphon bidenticola;
	Aphis coreopsidis, gossypii, spiraecola;
	Brachycaudus helichrysi;
	Geopemphigus sp. (Mexico, BMNH collection);
	Uroleucon ambrosiae, ambrosiae ssp. lizerianum,
	pseudambrosiae, tucumani
P. quinquefolia (?)	Aulacorthum solani; Rhopalosiphoninus staphyleae

Key to apterae on Parthenium:-

1	ANT PT/BASE less than 0.5. ANT V and VI with spinulose imbrication/reticulation. Eyes of 3 facets. SIPH absent. Paired spinal and marginal wax glands present	…..Geopemphigus sp.
–	ANT PT/BASE more than 1.5. ANT V and VI not spinulose. Eyes multifaceted. SIPH present. No discrete wax glands	…..2
2	ANT tubercles weakly developed, not extending forward beyond middle of front of head in dorsal view. ABD TERG 1 and 7 with or without marginal tubercles (MTu)	..…3
–	ANT tubercles moderately to well developed. ABD TERG 1 and 7 without MTu	..….5
3	Cauda helmet-shaped, not longer than its basal width in dorsal view, with a basal constriction. SIPH pale, smooth, with a subapical annular incision. Spiracular apertures large and rounded. ABD TERG 1 and 7 without MTu	…..Brachycaudus helichrysi
–	Cauda tongue- or finger-shaped, longer than its basal width, without a basal constriction. SIPH dark, without a subapical annular incision. Spiracular apertures small and reniform. ABD TERG 1 and 7 with MTu	…..4
4	SIPH 0.24-0.40 × BL, about twice as long as the much paler cauda. Head, ANT I, II and basal part of III very pale, contrasting with dark rest of ANT	..….Aphis coreopsidis
–	SIPH only up to 0.2 × BL. Cauda pale or dark. Head and antennal segments differently pigmented	…..go to key to polyphagous aphids, starting at couplet 22
5	ANT tubercles with smooth, divergent inner faces. SIPH dark except for basal 0.2-0.3 of length, tapering/cylindrical on distal half, with subapical polygonal reticulation extending for much less than 0.1 of length	…..Acyrthosiphon bidenticola
–	Without that combination of characters; if SIPH are mainly dark then they are either swollen distally or have polygonal reticulation on much more than 0.1 of length	…..6
6	SIPH wholly dark with polygonal reticulation on distal 0.25-0.4 of length. At least some of dorsal hairs arising from small scleroites	…..7
–	Without that combination of characters	…..go to key to polyphagous aphids, starting at couplet 4
7	SIPH usually at least 1.6 × cauda, which bears 7-12 hairs	…..Uroleucon tucumani
–	SIPH less than 1.5 × cauda, which bears 16-28 hairs	…..8
8	HT II rather long and thin, 6 or more × longer than its maximum thickness, 0.9-1.1 × R IV+V	…..Uroleucon pseudambrosiae
–	HT II less than 5 × its maximum thickness and 0.70-0.85 × R IV+V	…..Uroleucon ambrosiae

Parthenocissus	Vitaceae
Parthenocissus inserta	Aphis folsomii
P. quinquefolia	Aphis fabae, folsomii, illinoisensis, spiraecola;
	[Hysteroneura setariae]
P. semicordata	Greenidea parthenocissi;
	Neothelaxes parthenocissi, viticola;
	Sinomegoura citricola
P. tricuspidata	Aphis folsomii; Myzus ornatus; Neomyzus parthenocissi;
	[Sitobion akebiae]
P. vitacea = P. inserta

Key to apterae on Parthenocissus (except couplet 2, where only data for alatae are available):-

1	ANT 5-segmented, with ANT PT/BASE less than 1. SIPH as pores. Cauda with a midway constriction delimiting the distal part as a knob	…..2
–	ANT 6-segmented, with ANT PT/BASE more than 1.5. SIPH tubular. Cauda not knobbed	…..3

2	(Al.) ANT III with oval rhinaria arranged in a row. HT II tapering, with longest ventral hairs c.1.5 × maximum diameter of segment. ABD TERG 1-7 each with one pair of spinal hairs. ABD TERG 8 with 4 (-5) hairs	…..Neothelaxes viticola*
–	(Al.) ANT III with oval to annular rhinaria scattered over whole surface. HT II parallel-sided, with longest ventral hairs c.4 × maximum diameter of segment. ABD TERG 1-7 each with 3-6 spinal hairs, and ABD TERG 8 with 6 or more hairs	…..Neothelaxes parthenocissi*

3	SIPH 0.48-0.67 × BL and bearing numerous very long hairs. Longest hairs on ANT III more than 200 μm long, 5.5-7.6 × BD III	…..Greenidea parthenocissi
–	SIPH less than 0.3 × BL, without hairs. Longest hairs on ANT III less than 100 μm long, less than 3.5 × BD III	…..4
4	ANT tubercles well developed. ABD TERG 1 and 7 without marginal tubercles (MTu)	…..5

–	ANT tubercles weakly developed. ABD TERG 1 and 7 always with MTu	…..6
5	Dorsal abdomen with a large dark central sclerite on ABD TERG 2-4, large dark post-siphuncular sclerites present. ABD TERG 7 and 8 also heavily sclerotised, and with coarse, spinulose imbrication	…..Neomyzus parthenocissi
–	Dorsal abdomen membranous or with different sclerotisation	…..go to key to polyphagous aphids, starting at couplet 5

6	R IV+V with 8-10 accessory hairs. Cauda short and broad, about as long as its basal width, with more than 20 hairs	…..Aphis folsomii
–	R IV+V with 2 accesory hairs. Cauda much longer than its basal width, with 7-19 (-24) hairs	…..7
7	Hind tibiae wholly black. Longest hairs on ANT III 0.33-0.5 × BD III	…..Aphis illinoisensis
–	Hind tibiae mainly pale, with black apices. Longest hairs on ANT III 0.8-3.4 × BD III	…..Aphis fabae