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. 
| 
| pupa Percent- Aaee Percent- 
Distance from center. neces age of par- Distance from center. as ee age of par- 
collected.| @S!tism. | collected. | 2S!tsm- 
ASG CONTCT s. Ske. a het anes 20 DO DGS 5OMeCtco cae se ee tee eee So 50 0. 41 
HOMES T ere seis oe ee 66 245 6S4\\ e400 ee heme ha seats eee eee 70 18 
ROOweete a <a ee eee ee 78 D175 Al A50Mee beeen eee see ee 60 055 
150M CCH Aaa s2 Soe i eae 80 14434 |S 5O0MeCt lace were a eee a eee 70 42 
D00sf66t 22 2. eek eee eit ees 60 SPOS oUs eet eee ate 8 Met eee oe 70 - 00 
DOMES ies aks terre ee Bec ett 100 3°5OR| | RGU0 Mee bese ule Be eeee 70 - 00 
SOOMER bare ee cece tes eee eh 85 3. 44 
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 
apiece 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 
egos 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 larve. An equal number of small, 
wire-screen cages was prepared (Pl. XI, 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 Pl. XII, fig. 2, showing front and bottom of cage prepared for 
use in Anastatus colonizationin 1911.) 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. 
Karly in the fall of 1910 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 
little difficulty some 270,000 parasitized eggs have been secured, and 
were it not for the fact that the proper care in placing the number of 
colonies thus provided for will probably tax all available resources 
Se eee 
a> he 
