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Pomona College Journal of Entomology 



abdomen is dull green or brownish. Head — Small, nearly as long as wide, black. 

 Eyes — Rather large and very dark — from dark brown to almost black. Antennae 

 — (Figure 227 C). Reaching nearly to posterior end of the thorax, black through- 

 out except the base of article III, which is dull green. The lengths of the articles 

 are as follows: I, 0.06 mm.; 11, 0.068 mm.; Ill, 0.24. mm.; IV, 0.078 mm.; V, 

 0.12 mm.; VI, 0.2 mm.; total 0.766 mm. The last four articles are traversed by 

 large transverse sensoria which extend almost entirely around the articles and 

 which are distributed as follows: III with from ten to fourteen; IV, usually three; 

 V, three to five; VI, seven to eight. Rostrum — Dull green with dark base and tip, 

 reaching to the base of the second coxae. Prothorax — Black or dull greenish. 



Figure 228. Pemphigus populicaulis Fitch 

 Showing the galls from both dorsal and ventral aspects of the leaves. 



slightly wider than the head and narrower than the meso-thorax. Mesothorax — 

 Well developed with raised muscle lobes, black. Metathorax — Black with prom- 

 inent muscle lobe. Thorax covered with fine white powder. Abdomen — Oblong, 

 dull green to brown, covered with whitish flocculence and fine white powder, with 

 a row of darker spots along the lateral margins — a spot on each abdominal seg- 

 ment. Legs — Dark throughout, normal, slightly hairy. Wings — Subhyaline, 

 sometimes of a very dark cast, but always with a constant coloring. Primary — 

 Length 3 mm., width 1 mm. Costal vein dark and well defined to the stigma; 

 subcostal widening as it approaches the stigma, dusky; stigma nearly three times 



