118 THE SPRING GEAIN-APHIS OR ' ' GREEN BUG. ' ' 
The junior author foiuid that at Richmond. Ind., the adult Aphid- 
ins would Hve for at least two weeks when the temperature was 
below freezing. The parasites were taken into a warm room several 
times during these two weeks and they would become active, but 
when placed out of doors they would soon become numb. These 
adults were confined, however, so that excessive moisture was 
excluded, and they may not be able to live for so long a time in the 
fields unprotected. 
The fact that Aphidius can dining comparatively cold weather 
remain for a long period within the body of its host, and the latter 
give no external visible evidence of its presence, will readily account 
for the apparent absence of the parasite from any locality for an almost 
indefinite period: however, when the weather warms up sufficiently 
for development of the parasite to go on, its presence readily becomes 
apparent. For these reasons, as well as others that will be men- 
tioned in then proper places, it is impossible to say. from a cursory 
examination, that Aphidius is not present. 
INFLUENCE OF WINDS IX THE DISPERSION OF APHIDIUS TESTACEEPES. 
As the natural suppression of an outbreak of Toxoptera is more 
dependent upon the activity of this parasite than of any other of its 
natural enemies, it is important to learn the extent to which the para- 
site is able to follow its host in its spread from the South over the 
country to the northward. 
Dispersion of Aphidius may be accomplished in two ways — first, 
as larva? in the bodies of the 
winged host insect, where it is 
usually invisible, and. second, 
by being carried bodily with the 
winds along with the host . 
By referring to Table XII on 
page 10$, it will be observed that 
a number of cases are there 
recorded where individuals of 
Toxoptera graminum which were 
Fig. 2^.— Winged female of tne spring grain-aphis, \ . f 7 
parasitized bv Aphidius Usicceipes. Enlarged. parasitized developed tO Winged 
(Prom Webster.) Mte, ^^ fQJ . ft ^^ Q$ 
eight or nine days, and during this time gave birth to young, but 
from their dead bodies Aphidius afterwards issued. The pres- 
ence of winged parasitized females on the leaves of grain and grasses 
inhabited by Toxoptera is of common occurrence (see fig. 29). Thus, 
while it has not been possible to observe the parasitism of individuals 
and follow out the final dispersion of the same, the evidence tending 
to show the probability of its general occurrence is so overwhelming 
that such direct proof does not seem necessary. With the obscurity 
