592 Pomona College Journal of Entomology 



light yellow witii dark tips, tarsi dark. Style (I'ig. 192, d and e) — Conical or 

 nearly cj'lindrical, hairy, dusky green to dark brown, length 0.13 mm. 



Young — Dark green or brownish. Some are slightly' pruinose. 



Ilo.sts — Tiiis insect lias been taken in this locality only upon the tender 

 growth of or.mge trees. Near Pomona it was found by the writer several years 

 ago in great numbers feeding ujion the tender shoots of young Valencia trees. 

 At Santa P;iula it has been found only upon tlie suckers of the Havana Seedling 

 Sweet Orange. 



This insect is indeed .i x ery extensive feeder and has been taken from over 

 (ifty different plants throughout tlie United States. It was originally found upon 

 the cotton |)lant and h.is since ])roven a great melon pest. It is known by thi- 

 counnon names "Cotton Aphis" and "Melon .\))his." In this jjarticular locality 

 there are numerous melon vines growing near orange groves which have been 

 infested with this louse, but I have never yet found a single vine infested with 

 this louse. I recently received a siii])nient of eight distinct species of plant lice 

 from ImpAial County, where the melons suffer from their depredations, but none 

 of them proved to be this species, although tliis does not prove that it does not 

 exist in that locality. It was not the most abundant this year if I may judge from 

 this sending. 



Locality — On citrus trees throughout this State and also reported on various 

 otlier plants. Taken in Orange. Los Angeles, San Bernardino and Ventura Coun- 

 ties by the writer. 



Date of Collection — This species, like To.roptera aurant'iae Koch, is most 

 abundant during the early spring months from February to .Tune. Collected in 

 large numbers at Santa Paula, May 17, 1911- Serial number fj. 



Natural Enemies — Subject to the attacks of the same natural enemies as are 

 described under To.roptera aurantiae Koch. 



In the Pomona College Journal of Entomology, N'ol. I, pp. I-T-IS, 1909, I 

 described this insect as Aphis citri Ashmead. In the same Journal, Vol. II, 

 pp. 22,S-2'21', 1910, the species described as Aphis gossypii Glover has proven to 

 be a new and distinct species and is herein described as Aphis cookii n. sp. 

 resembling the Pea and Rose Aphids. 



Macrosiphum citrifolii ( .\shniead ) 

 1882 Siphonophora citrifolii Ashmead, Can. Ent. Vol. XI\'. p. 92. 

 WINGED viviPARoi-s FEMALE (Figure 193 A) 



I.engtii not including style 2.2 mm., width of mesothorax 0.7 mm., greatest 

 width of abdomen 0.9 mm., wing expansion 9-0 mm. A large green louse greatly 



I'revailing color — Brigiit pea green, shiny. Head — Slightly wider than long, 

 amber to pinkish yellow in color, with rather large antennal tubercles. Eyes — Red. 

 Antennae — (Figure 191' a). On rather large tubercles, longer than the body, with 

 very few hairs, articles I and II dusky green. III dusky amber witli evtreme base 

 light, IX , V and VI dusky throughout; the lengths of the articles are as follows 

 (although these vary greatly) : I, 0.1 1- mm.; II, 0.08 mm.; Ill, 0.7 !• mm.; IV, 0.7 



