A SYNOPSIS OF THE APHIDIDAE 37 



This species has been reported by Essig from Ventura County. 

 The author has never taken the alates, but has had the opportunity 

 of examining Essig 's specimens, and specimens from Montana and 

 Utah taken by Haegele and Doane. It is easily distinguished from 

 other members of the genus by the broad, dark wing veins. 



35. Thomasia salicicola (Essig) 



Figure 78 



Essig, Pom. Jour. Ent., vol. 3, p. 532, 1911. Chaitophorus (orig. desc.). 

 Davidson, Jour. Eeon. Ent., vol. 3, p. 375, 1910. ChaitopJiorus nigrae Oest- 



lund (?) (list). 

 Davidson, Pom. Jour. Ent., vol. 3, p. 398, 1911. Chaitophorus nigrae Oest- 



lund (?) (list). 



Essig, Pom. Jour. Ent., vol. 4, p. 619, 1912 (note). 

 Essig, Pom. Jour. Ent., vol. 4, p. 716, 1912 (list). 



Eecords. Salix laevigata, Santa Paula (Essig), Salix nigra, Lakeside, San 

 Diego County, April, 1916; Populus trichocarpa, Santa Paula (Essig); Salix sp., 

 Sau Jose, Stanford University, Penryn, Placer County (Davidson), Fillrnore, Ven- 

 tura County, March, 1911 (Essig). 



Essig reported this from Ventura County, and the author has 

 found it in San Diego County. It was observed to be in large colonies 

 on the leaves and leaf petioles of the tender growth of willow, in 

 company with Siphocoryne carpreae (Fabr.). Specimens taken by 

 Davidson and listed as Chaitopkorus nigrae Oestlund prove to be 

 identical with this species. 



16. Genus Symydobius Mordwilko 



Mordwilko, Bap. Lab. Zool. Kap. Imp. Varch. Univ., 1895. Type Aphis 

 oblonga Heyden. 



KEY TO CALIFORNIA SPECIES 



1. Anal plate half -moon-shaped 2 



Anal plate bilobed (fig. 271) ; cornicles pale, appearing white in life; antennae 



with about six to eight secondary sensoria on III, and one or two on IV 

 (fig. 272 ) chrysolepis Swain 



2. Spur of VI but a short thumb-like projection ; sensoria on III numbering about 



six to ten; none on IV agrifoliae Essig 



Spur of VI longer, being equal to or longer than base of VI ; fifteen to twenty 



sensoria on III, one or two on IV (figs. 73, 74) 3 



3. Antennae for the most part dark, being dark brown or black; spur and base 



of VI equal, lateral abdominal tubercles present in apterae. 



macrostachyae Essig 



Antennate for the most part pale, being light brown or amber; spur of 



VI usually slightly longer than base; apterae without lateral abdominal 

 tubercles salicicorticis Essig 



