TACHINID PARASITES OF THE GIPSY MOTH. 217 
been made for cold storage in transit, with the results as mentioned 
above. 
A very large number of the parasites were secured in this manner, 
and several thousands of the maggots were allowed to enter the earth 
in the open in forests infested by the gipsy moth. Others were allowed 
to pupate in a natural manner in forest soil or in a mixture of garden 
loam and sand in a variety of containers in the laboratory grounds. 
An examination of these puparia was made from time to time dur- 
ing the winter and they were found to be uniformly in a much more 
satisfactory condition than the hibernating puparia had ever before 
been at that season of the year. So far as could be determined even 
up to within a few weeks before the emergence of the flies would 
naturally take place, there was no difference in the condition of the 
puparia hibernated in different kinds of soil or under slightly different 
environment. 
Beginning quite early in the spring and continuing through a con- 
siderable period, flies emerged in very variable proportions from the 
different lots of puparia. The emergence in a few instances was well 
up toward 100 per cent. In others it was much lower, and in a few 
none of the flies completed their transformations. The reasons for 
these differences were not obvious in every instance, but it was ob- 
vious that unless conditions are practically identical with those which 
prevail in the open, the flies will fail to issue in the spring. Moisture 
is an essential, but is by no means the only essential to success. Nor 
can failure be attributed to unduly high or low temperatures, or un- 
natural and abrupt changes in the temperature during the period of 
hibernation. 
The average percentage of emergence from all of the different lots 
of pupe has not been as yet accurately calculated, but it was far in 
excess of any that was secured before, and three colonies which were 
considered to be satisfactorily large and strong were established in 
different parts of the infested area. It was not really expected that 
any of the new generation would be recovered from the field during 
the course of the first season, and it was therefore considered a par- 
ticularly good omen when a few were recovered, without difficulty, 
and under conditions which indicated that dispersion at a quite rapid 
rate had accompanied a rapid rate of increase. The species has not 
yet been placed on the list of those considered as thoroughly estab- 
‘lisbed, since it is not certain that it will pass through the complete 
seasonal cycle in the field, but it is confidently expected that it will 
live through successfully and that it will be recovered in 1911 in larger 
numbers. If these expectations are realized there is every reason to 
believe that it will become a parasite of consequence within the next 
five years. 
