•28 
lice obtained at this time were found chiefly among the husks o[ 
nubbins and in crannies between the ensheathmg part of the leaves, 
They were evidently restless, and the warmth of the sun at midday 
aroused some of them to endeavors to find better quarters. These 
were found wandering about the stalks. An almost microscopic ex¬ 
amination of stalks which had supported thousands of aphides was 
made after the lice disappeared without finding an egg. The root 
form of the corn louse has not to my certain knowledge been ob¬ 
served later than October 8. Its period has probably passed and 
its purpose been served when the warm weather of July comes on, 
and with it the aerial form. But to make sure as to whether or 
not this form was hibernating in the ground, the roots of weeds, 
grasses and corn in cornfields were searched in November, but with¬ 
out finding them. In the same fields at this time, the hibernating 
viviparous females of Schizoneura panicola were abundant on the 
roots of blue grass and timothy. 
From these observations, it seems to me evidently either that (a) 
Aphis maidis matures its egg-laying brood locally; ( b ) that this brood 
matures on some plant other than corn, or (c) that the brood appears 
at intervals greater than one year, the species being in the mean¬ 
time maintained by hibernating viviparous individuals. 
(a) The area over which the foregoing observations were made 
will doubtless be quite uniformly infested early the coming spring 
with corn plant lice. That these lice can have been so distributed 
over so extensive an area, and at so early a date after hatching 
from the eggs of locally developed oviparous females, can not be 
believed. 
(■ b ) If eggs were produced on some plant other than corn, it must 
have been by plant lice born of the viviparous females which de¬ 
serted the corn. The development of such a brood would have been 
possible even after the first of November; for Aphis mail matured 
its oviparous brood on the apple trees after this date. When the 
winged viviparous females of the corn louse began to mature rapidly 
and scatter through the fields in the fall, close watch was kept of 
available plants to see whether or not the lice resorted to them for 
this purpose. Volunteer corn, which grew up along railroads late 
in the season, became almost invariably stocked by these migrating 
individuals, but on no other plant could the adults and young be 
found. Wheat, oats and the perennial grasses seemed to be the 
most likely to be resorted to, and the roots and stalks were 
thoroughly examined. The lice peculiar to these plants were often 
found in very great numbers, but in not a single instance was any¬ 
thing found established on them which could be taken for Aphis 
maidis. 
(c) The hypothesis that the lice hibernated as alate viviparous 
females was the only one, then, left to me, and though not thoroughly 
satisfied with the nature of the evidence, I am disposed to believe 
that this is the usual manner of passing the cold months, and that 
the oviparous brood appears only under specially favorable circum¬ 
stances, perhaps locally. This conclusion is held subject to revision. 
It is what seems most probable with the results of two seasons ob¬ 
servation before me. 
