708 Pomona College Journal of Entomology 



;ivera{j<' wing expanse of tlie species as taken here is slightly over 10 mm. All 

 measurements were made with a camera lucida. 



Antennal Articles — Antennal articles I, I(, I\' and X are given subeqiial, 

 while I have found that I and II are nearly equal and that IV' and V are prac- 

 tically sub-equal, but that the articles IV and V are much longer than I and II 

 (nearly twice as long or a third longer). Articles III and VI correspond very 

 well. 



Rostrum — In the specimens taken here tlie rostrum rarely reaches beyond 

 tlie second coxa". Thomas reports it as reaching to the third coxae. 



JVitigs — The venation of the wings agrees very well in all respects except 

 the shape of the stigma. I have found it well rounded or nearly oblong instead 

 of angular. 



Though these differences are considerable, the general descriptions agree 

 well and I feel perfectly satisfied that the species is as named. No doubt that 

 with our early warm springs the young develop more lustily and this may account 

 for tile difference in size, which may also influence other characters. 



Pemphigus populicaulis I'itch 

 (The Poplar-stem Gall-louse) 

 1859 Fitch. Kept. Ent. N. Y. V, pp. SL-j-Siy. Original description. 

 1868 Walsh-Riley. Am. Ent. Ill, p. 57 and )). 245. Description and notes. 

 187S Le Baron. Rept. Ent. 111. Ill, p. 193. Notes. 



1879 Thomas. 8tii Re])t. Ent. 111., j). 1 19. Description. 



1880 Henry. Am. Ent. I, p. 205. Reference to galls. 



1886 Oestlund. List Aphid. Minn., p. 55. Listed. 



1887 Oestlund. Aphid. Minn. p. 21. Description. 

 1890 Packard. Forest Insects, p. kSl. Listed. 

 1892 Osborn. Cat. Hem. la., )). l.'iO. Listed. 

 1895 Cowen. Cat. Hem. Colo., p. 1 15. Li.sted. 

 1901 Hunter. Aphid N. A., p. 78. Bibliography. 



190.3 Cook. Ohio Natural. IV, pp. 118-2tO. Bibliography. 

 1903 Clarke. List. Cal. Aphid.. Can. Ent. XXXV, p. 1 31..' Listed. 

 1908 Vickary. Comp. Study of Ext. Anat. Plant Lice, pj). 4-5 and 15. 

 Anatomy. 



1908 Jackson. Syn. Gen. Pemphigus. Proc. Col. Hort. Soc., pp. 51' and 



83-86. Description and notes. 



1909 Davidson. Aphid. In \'ie. Stanford Univ.. Jr. Ec. Ent. vol. II, ]). 



299. Listed. 



1910 Davis. III. Aphid. .Fr. Ee. Ent., Ill, p. HI. Li.sted. 



1910 Williams. Aphid. Nebr., pp. 9-10. Descri])tion and notes. 



1911 Essig. CaliL Aphid. P. C. Jr. Ent. Ill, p. 1.61. Calif. Hosts. 



winged viviparous female (Figure 227 A) 

 Length of body 2 nun., width of tliorax 0.() nnu., width of abdomen 0.75 mm., 

 wing expansion 6.7 mm. Prevailing color — Nearly black body almost or entirely 

 covered with a long whitish flocculence which gives the body a bluish tinge. The 



