SUBFAMILY APHINAE ZL 
soria fewer than 13 on III (7-12), hind tibia shorter than .90 (.70) and hind tarsal 
II shorter than .11 (.07-.08). However, since occasional small individuals of the 
form here described hardly differ from the above measurements no definite 
distinguishing line can be drawn between the plum and the apple forms; but 
since the form here treated has not been taken on plum in this region in forty 
years of collecting it appears advisable to use a name of an aphid described from 
apple. 
Rhopalosiphum grabhami Cockerell 
Rhopalosiphum grabhami Cockerell, 1903b:342; Gillette and Palmer, 1932b:483. 
Alate Vivipara. Head and thorax black; abdomen dark olive-brown; tibiae pale with 
tips black :/ antenna, cauda and cornicle dark. Body length 2-2.20; hind tibia 1.1-1.2; hind 
tarsal II .09-.10; antenna 2.25, secondary sensoria convex; rostrum obtuse attaining between 
lst and 2d coxae. Hairs slightly capitate. Cornicle club-shaped, at middle twice as wide as 
hind tibia and with flange. Cauda acute, tapering, hardly longer than wide, often appearing 
somewhat constricted near tip, bearing 2 lateral pairs and 1 dorsal pair of hairs. 
| "36 ee) 
Fig. 253. Rhopalosiphum grabhami 
Collections. On Lonicera utahensis and involucrata, curling leaves longitud- 
inally. Colorado: Eldora and Cameron Pass. New Mexico: Pecos. Utah: Mount 
Timpanogos, Eden and Logan. Alatoid nymphs June 24, alate viviparae June 25 
to July 26, oviparae Aug. 21; all collections consisting of numerous alate speci- 
mens; not common. 
The fact that all the numerous viviparous individuals of the collections 
taken were alate forms is suggestive that migration to a summer host was taking 
place. R. poae on Poa agrees very closely with this species and might seem to 
qualify for the form on the alternate host but poae has not been taken on grass 
in the summer. More study is needed to settle the question. 
Cotypes. U.S.N.M. 
Rhopalosiphum maidis (Fitch) 
Corn Leaf Aphid 
Aphis maidis Fitch, 1856:550; Forbes, 1885:25; Davis, 1909b:144; Wildermuth and 
Walter, 1932:1; Gillette and Palmer, 1932b:415. 
Rhopalosiphum maidis, Webster, 1887 :148. 
Apterous Summer Vivipara. Pale bluish green, darker on area about cornicles, brownish 
anteriorly, darkest on head, old adult apterae darkest; covered with slight powder. Body 
length 1.30-1.75, rather slender; hind tibia .55-.60; hind tarsal II .09-.1; antenna .60-.70. 
Fig. 254. Rhopalosiphum maidis 
Alate Vivipara. Head and thorax black; abdomen pale green with dusky lateral areas on 
abdominal segments anterior to cornicles, and dorsal dashes posterior to cornicles; cornicle, 
cauda and appendages dusky. Body length 1.77-2.5; hind tibia .75-.80; antenna .90-1; rostral 
IV+V broad, hardly attaining 2d coxa. Cornicle slightly-incrassate, with slight constriction 
next to slight flange, imbrications slightly serrate. Cauda approximately parallel-sided with 
rounded tip and distinct but broad neck and bearing 2 or occasionally 3 hairs on each side. 
