836 
ANNUAL REPORT. OF NEW YORK 
APHIS. BECOMES GREGARIOUS AND YELLOW COLORED IN SUMMER. 
in this insect, whereby it appears to be another creature, a differ¬ 
ent species in summer from that which is seen in the spring. 
Before the heads appear it lives singly, scattered about upon the 
leaves and stalks of the grain, and the young lice as fast as they 
are born leave their parents and wander away. But no sooner 
are the heads protruded from their sheaths, preparatory to bloom¬ 
ing and growing the kernels of the’grain, than this aphis wholly 
forsakes the other parts of the plant, and becomes congregated 
here upon the heads, evidently because the juices which the plant 
elaborates for the growth of its flowers and seeds are much more 
nutritious, dainty and palatable to these insects than those which 
circulate in the leaves and stalks. They here fix themselvos on 
the base of the chaffs which envelope the kernels, standing with 
their heads downwards, and inserting their bills, they suck out 
the juices which should go at first to grow the flowers, and after 
that to fill and perfect the kernels. And now the young lice, 
instead of scattering themselves and traveling away, settle down 
closely around their parent, crowding as compactly together as 
they can stow themselves. Thus it came to pass that in most 
of our grain fields last summer, scarcely an ear could be found 
that had not a cluster of these lice around the base of almost 
every kernel, all with their tiny bills inserted therein, pumping 
out the juices which should go to swell and perfect the seed. 
Thus, from being a solitary insect, wandering about singly on 
the leaves and stalks, it became a gregarious insect, clustered 
together and stationary upon the lower or butt ends of the 
kernels. 
At the same time an equally remarkable change took place in 
the color of these insects. So long as they nourished themselves 
on the coarse juices of the leaves and stalks, they were all of a 
grass green color. When they came to feed on the more delicate 
juices of the flowers, they began to change to an orange color. 
One of the grass-green insects having stationed herself at the 
base of a kernel, next day, in the group of little ones around her, 
a yellow one would occur, all the others being green liko their 
parent. A day or two later, as the nourishment she had derived 
from the leaves became more dissipated from her body and repla¬ 
ced by that now obtained from the kernels, half the young she 
produced would be of this yellow color. And still later all the 
young would be yellow, no green ones being afterwards born. 
