174 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 
Table VIII. — Average percentage of parasitism of gipsy-moth egg masses at different 
distances from center of colony. 
Distance from center. 
Number 
of egg 
masses 
collected. 
Percent- 
age of par- 
asitism. 
Distance from center. 
Number 
of egg 
masses 
collected. 
Percent- 
age of par- 
asitism. 
At center 
20 
66 
78 
80 
60 
100 
85 
29. 26 
24. 68 
21.75 
14. 43 
8. 61 
3. 59 
3. 44 
350 feet 
50 
70 
60 
70 
70 
70 
0. 41 
.18 
.055 
.42 
.00 
.00 
50 feet 
400 feet 
100 feet 
450 feet.. 
150 feet 
500 feet 
200 feet 
550 feet 
250 feet 
600 feet 
300 feet 
When in the fall of 1909 it had become rather certain that the rate 
of dispersion of Anastatus was only going to be about 200 feet per 
year, plans for colonization along very different lines in 1910 were 
immediately put into execution. In four of the five colonies all of 
the egg masses which could be easily secured were collected and 
brought to the laboratory, where -the eggs were separated from their 
hairy covering. This is best effected by gently rubbing them over 
a piece of cheesecloth stretched on a frame. (PL XX, fig. 2.) 
The hairs pass through and the eggs are left. 
The number of parasitized eggs present was then estimated, and 
found to be very close to 90,000. In the spring, after all of the healthy 
eggs had hatched, those remaining, including all which were para- 
sitized, were divided into 100 lots, each of which was supposed to con- 
tain approximately 900 parasite larvse. An equal number of small, 
wire-screen cages was prepared (PI. XII, fig. 1), and about the middle 
of June, when the male parasites began to issue, and when it was 
becoming possible to determine with some degree of assurance just 
where there were likely to be large numbers of gipsy-moth eggs a 
little later, the work of placing these cages in the open was begun. 
(See also PI. XII, fig. 2, showing front and bottom of cage prepared for 
use in Anastatus colonization in 191 1 .) They were finally placed, each 
in a separate locality, and each, so far as has been determined by sub- 
sequent investigation, in localities where the parasites had an excel- 
lent opportunity to work to the best advantage as soon as they issued. 
Not all of these colonies have since been visited, and probably some of 
them never will be seen again, but all that have been examined have 
been found in the best of condition. 
Early in the fall of 1 910 the dispersion studies of 1909 were repeated , 
with results which have already been indicated in Mr. Wooldridge's 
diagram, and the egg collections were also repeated for the purpose 
of securing material for additional colonization work in 1911. With 
lit tie difficulty some 270,000 parasitized eggs have been secured, and 
were it, not for the fact thai the proper care in placing the number of 
colonic- thus provided for will probably tax all available resources 
