186 
PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 
The reproduction of the parasite in the field as a result of these 
early attempts at colonization was far in excess of expectations. 
The rate of reproduction in the laboratory (as indicated in the table) 
was greatly exceeded in the open, and hundreds of thousands of eggs 
in the immediate vicinity of the colony sites were known to be 
parasitized when the coming of cold weather put a stop to insect 
activity. In the one colony which was most closely watched, the 
parasitized eggs averaged some 30 to the mass (fig. 27), while every- 
where within 50 yards of the center egg masses were so thick in spots 
as to hide the bark on the trees. 
Beyond the distance mentioned the 
number per mass fell off very rapidly, 
but some were found several hundred 
yards away from the point of libera- 
tion, in striking contrast to the re- 
sults following the colonization of 
Anastatus. 
In October adults of what ap- 
peared to be the second generation 
were not uncommon in the field, and 
on any warm day they could be 
found, apparently ovipositing for a 
third generation. At the same time 
larvae and pupae were in abundance, 
and only a few days' exposure to the 
warmth of the laboratory was needed 
to bring them out from eggs collected 
in the field. Collections of eggs were 
made from time to time during the 
fall, in order that assurance might 
thus be had of the continued well- 
being of the parasite, and until De- 
cember nothing untoward occurred. 
The first real winter weather came 
^ „_ ^ , . , at the end of that month, and a few 
Fig. 27 —Gipsy-moth egg mass, showing exit holes 
of Schedius kuvanse. Enlarged about four times, days later a lot OI eggS Was COl- 
(0riginal } lected and brought in. Not a sin- 
gle parasite issued. The experiment was repeated and with the 
same results, and although many hundreds of masses have since been 
collected (some of them in the spring, after the caterpillars had 
issued for the purpose of determining whether there might not be 
reproduction of hibernated adults at that time, and the rest of them 
in the fall to see if by any chance the parasite had escaped detection 
in the spring), no trace of its existence could be found. In every 
