4 BULLETIN 112, IT. S. DEPARTMENT OF AGRICULTURE. 
the} T soon change to shining black and retain this color until they 
hatch in the spring. 
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, by 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 (Macrosiphunv granarium Kirby) is 
larger than Aphis avence 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 
Bond.), is more nearly the size of Aphis avence, 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 avence 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 sorhi 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 
