4 BULLETIN 112, U. S. DEPARTMENT OP AGRICULTURE. 



the} 7 soon change to shining black and retain this • color until they 

 hatch in the sj)ring. 



SPECIES LIKELY TO BE CONFUSED WITH THE OAT APHIS. 



This species may be recognized in the grain field by the pinkish, 

 orange, or reddish areas on the abdomen at the bases of the cornicles. 

 It may also be distinguished by the wing venation, by the short, 

 slightly swollen cornicles, hy the mottled pattern of coloration of 

 the abdomen, and in the winged form by the rows of black spots on 

 either side. The antennae also differ from those of other species. 



The large green grain-aphis (M acrosiphnm- granarium Kirby) is 

 larger than Aphis avenw and does not have the colored areas at the 

 base of the cornicles. These last are longer, reaching nearly to the 

 tip of the cauda, or tail, and are more cylindrical, and the antennae 

 are longer in relation to the length of the body. 



The spring grain-aphis, or "green bug" (Toxoptera graminum 

 Kond.), is more nearly the size of Aphis averue, but it need not be 

 confused with that species if we remember that it is pale green, about 

 the color of the wheat leaf, and that this coloration is quite uniform 

 over the entire abdomen ; that it does not have the orange or reddish 

 areas at the bases of the cornicles; and that the winged female is 

 without the black spots on each side of the body. Further, the 

 venation is ordinarily different in the two species, the median vein 

 of avence (fig. 3) being twice branched, except in rare instances, 

 while in the " green bug " (fig. 4) it is but once branched. 



Aphis averwz is readily distinguished from other aphides on apple. 

 Aphis pomi De G., the most common apple aphis, is quite different, 

 the wingless individuals being uniformly pale apple green with black 

 and rather conspicuous cornicles and no trace of orange or pink on 

 the abdomen about the cornicles. The winged individuals are simi- 

 lar, except that the head and thorax are shining black and the abdo- 

 men pale apple green ; also the venation of the wing is different, the 

 last branch of the median vein not dividing near the apex of the 

 wing. This aphis spends its entire life cycle on the apple and related 

 trees. 



The rosy apple aphis (Aphis sorbi Kalt.) varies greatly in color 

 from the greenish blue, pulverulent females hatching from eggs to 

 the more or less pinkish forms. It is slightly larger than the oat 

 aphis and does not have the pinkish or orange areas about the bases 

 of the cornicles, although the distal end of the abdomen may be 

 pinkish, and in some stages, such as the pupal stage of the spring 

 migrants, the entire body may be pinkish or salmon colored. The 



