SUBFAMILY APHINAE 279 
mined by him as his species with the suggestion that the markings might rep- 
resent varieties. Our specimens were taken mostly on R. aureum and his on 
R. cynosbati. 
Considerable variation in different characters exists in the Rocky Mountain 
form alone but repeated attempts, with about 200 specimens, to separate it into 
2 or more species have failed, due to lack of corellation between the variations 
of the different characters as well as to the gradual intergrading of intensity of 
characters. No definite lines of distinction could be drawn so the group is 
tentatively left as one variable species. It is here placed under cynosbati on 
account of occasional specimens which agree with Oestlund’s type specimens. 
_If the Rocky Mountain form is specifically distinct it should perhaps be placed 
under K. alpina, but biological evidence of acceptance of the same hosts has not 
yet been obtained. 
Kakimia essigi (Gillette and Palmer) 
The Black-backed Columbine Aphid 
Myzus aquilegiae Essig, 1917:314 (preoccupied) ; Knowlton, 1929b:10. - 
Myzus essigi Gillette and Palmer, 1929a:30 (new name for M. aquilegiae Essig). 
Apterous Summer Vivipara. Pale yellow-green to straw-yellow with patch of shining 
black on entire dorsum of abdominal I to V and on median portion of V and usually with 
broken dashes on remaining abdominal segments; appendages pale. Body length 1.70-2.5; hind 
tibia 1.6-2; antenna 2.10-2.5; rostrum attaining 3d coxa. Hairs slightly capitate; on side of 
_ body .04. Cornicle cylindrical, imbricated. Cauda tapering, bearing 2 pairs of lateral hairs 
and a single dorsal preapical one. 
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Fig. 335. Kakimia ‘essigi 
Alate Vivipara. Head and thorax blackish; abdomen pale yellow-green to straw-yellow 
with lateral areas and dorsal speckles and broken dorsal patch black; antenna dusky except 
base of III; other appendages pale. Measurements as in apterous vivipara. Hairs slightly 
capitate or blunt; not evident on body. 
Ovipara. Apterous. Body length 1.70; antenna and cornicle as in apterous summer vivi- 
para; hind tibia 1.05, proximal two-thirds swollen slightly and bearing numerous, small 
sensoria. 
Male. Alate. Color about as in alate vivipara except appendages somewhat darker. 
Body length 1.50-1.70; antenna 2-3; cornicle .25; hind tibia 1.25-1.50. 
Collections. On leaves of Aquilegia coerulea and A. rubicunda. Colorado: 
Longmont, near Cameron Pass, Pingree Park, Boulder, Fort Collins and nearby 
foothills. Utah: Monte Cristo and Vernon Canyon. Alate and apterous vivi- 
parae June 12 to Nov. 29, sexuales Oct. 3 to Nov. 29; commen. 
Cotypes. Essig and Colo. Agr. Exp. Sta. Collections. 
Chief Distinguishing Characters. Conspicuous dorsal patch on abdomen 
especially of apterous vivipara, length of cornicle (2-3 times rostral IV+V), 
length of hind tarsal II (shorter than rostral IV+V) and length of unguis 
(slightly exceeding length of III). 
