HATCHING OF GIPSY-MOTH EGGS. 13 
collected there had each year shown a high percentage of parasitism. 
After the above-mentioned cold winter the parasitism was of de- 
cidedly lower percentage, but two 3'ears later it had about reached 
its former high point. 
In the long run it is doubtful if the cold would have any very 
serious effect upon the general abundance of Anastatus Mfasciatus. 
Even though all the parasites as well as all the eggs above the 
snow protection line were killed, the proportion of parasites to 
eggs would be the same in those ^gg clusters protected by the snow, 
for there is very little difference in percentage of parasitism be- 
tween eggs near the ground and those above 5 feet. Therefore, 
there would be the same proportion of adult parasites to attack the 
eggs the next summer as if all parasites and all eggs came through 
the winter safely. 
As the result of particularly adverse conditions a decrease in 
parasitism by Anastatiis hifasciatvs, such as was evidenced at the 
stock colom^, may occur for a few years, but no doubt there is a 
gradual recovery. 
Schedius huvanue has received some rather severe setbacks from 
cold winters. It hibernates as an adult, principally in leaves "and 
rubbish on the ground, and in such position it would be well pro- 
tected from the cold if there was plenty of snow during each period 
of extremely low temperature. Apparently such protection has not 
been present in- a number of cases, for there are records of colonies 
from which recovery of parasites was difficult after a severely cold 
winter. 
Some of the other imported parasites may be killed by low tem- 
perature, but very little information has been obtained to confirm 
this idea. 
Further investigations may throw more light upon the relationship 
of low temperature to parasite mortality. 
CONCLUSIONS. 
The failure of gipsy-moth (^gg clusters to hatch is caused by low 
temperature. 
An exposure of between —20° and —25° F. is necessary to kill 
entire clusters, though some eggs in each cluster may be killed by an 
exposure to — 15°. Xo esas will survive an exposure to lower than 
-25^°. ^^ 
AThen the temperature is low enough, an average of TO per cent 
of the clusters may be killed, but this desirable condition develops 
only in the northern part of the infested area and only during cer- 
tain years. 
Snow will protect the ^gg clusters from the effects of the cold if 
it covers them: therefore, the greater the depth of snow the larger 
the number of clusters that will hatch the following spring. 
The benefit derived from nonhatch may vary after a cold winter 
from 70 per cent of the clusters kille'd in the northern part of the 
area to no injury to the eggs in the southern section. 
Maine and Xew Hamxpshire receive the greatest benefit from non- 
hatch. Central and northern Massachusetts also derive considerable 
benefit particularly in restricted localities. Connecticut, Ehode 
