A SYNOPSIS OF THE APHIDIDAE 41 



41. Pterocomma populifoliae (Fitch) 



Figures 82. 83 



Fitch, Cat. Homop. N. Y., p. 66, 1851. Aphis (orig. dese.). 



Davidson, Jour. Econ. Ent., vol. 2, p. 300, 1909. Cladobius rufulus n.sp. 



(desc.). 

 Davidson, Jour. Econ. Ent., vol. 3, p. 375, 1910. Cladobius rufulus Dvdn. 



(list). 

 Essig, Pom. Jour. Ent., vol. 4, p. 786, 1912. Melanoxantherium rufulum 



(Dvdn.) (desc.). 

 Wilson, Ann. Ent. Soe. Am., vol. 8, p. 353, 1915. Pterocomma populea 



(Kalt.) (desc.). 

 Baker, Can. Ent., vol. 48, pp. 280-282, 1916 (desc.). 



Records. Salix sp. ; Stanford University (Davidson); Santa Paula (Essig); 

 Walnut Creek, March, 1915 (Davidson) ; Grossmont, San Diego County, March, 

 1916; Lakeside, San Diego County, April, 1916; Stanford University, May, 1912 

 (Morrison); Populus sp. ; Stanford University (Davidson); Palo Alto, March, 

 1915; Populus caroliniana, Banning, Riverside County, April, 1917. 



This is a widely distributed species in California on various species 

 of poplars and willows. Davidson first found it in 1909, describing 

 it as a new species. In 1915 Wilson stated that it was synonymous 

 with P. populea (Kalt.), but specimens sent him by the author he 

 determined as P. bicolor (Oestlund). According to his paper the 

 cornicles of populea (Kalt.) are about equal in length to the hind 

 tarsi. Californian specimens have the cornicles considerably longer 

 than the hind tarsi, but not twice as long as he states they are in 

 bicolor (Oestlund). His figures of the antennae show that in populea 

 VI base and spur are subequal, and in bicolor the spur is considerably 

 longer than the base. The latter is true for the Californian species. 

 His color notes of populea fit the Californian species very well. Baker 

 identified Aphis populifoliae Fitch as a Pterocomma and places 

 rufulus (Davidson) as a synonym. From a study of specimens taken 

 in Santa Paula, Grossmont, Lakeside, Stanford University, and Wal- 

 nut Creek, the author finds that Baker's description of populifoliae fits 

 this species very well. Below are the measurements in microns of 

 four alate specimens, together with the measurements of cornicles, 

 antennae, and hind tarsi of one from Lakeside. (This was preserved 

 for several months in alcohol before being mounted for study, and had 

 shrunk considerably.) 



An examination of the following table shows that in the California 

 specimens the cornicles are always considerably longer than the hind 

 tarsi, but never twice as long, and that the spur of six is always longer 

 than the base, except in one case. This specimen is considerably 



