EGG PARASITES OF THE GIPSY MOTH. 185 
began to increase rapidly in numbers with each succeeding generation. 
By August there were enough to make a small colony in the open 
possible without depleting the laboratory stock to a serious extent, 
and first one and later several small colonies were established in 
various localities in the moth-infested area. 
At the same time reproduction work was continued on an ever- 
increasing scale at the laboratory, and by the first of the next year 
no less than 1,000,000 individuals, at a conservative estimate, were 
present in our rearing cages. Further attempts to increase this 
number were not successful, on account of the difficulties attending 
the handling of such an immense number at a time when the hatching 
of the host eggs followed too soor. after their removal to high tem- 
perature. 
The numbers in the laboratory suffered no decrease, however, and 
by the end of March colonization work on an extensive scale was 
begun. The parasitized eggs were divided into 100 lots, each of 
which contained approximately 10,000 of the parasite, and these 
were distributed to agents of the State forester’s office, who placed 
them in the field in the hope and expectation that the parasites 
issuing from them would reproduce immediately upon the gipsy-moth 
eggs before the latter hatched. 
There was also a large quantity of parasitized eggs remaining, and 
these were placed in cold storage in the hope that the emergence of 
the brood might be retarded until the fresh eggs of the gipsy moth 
should be available for attack in the latter part of the summer. This 
hope was not justified, because when the time came and the eggs 
were taken from cold storage not a single living parasite remained. 
In Table IX are summarized the results of the reproduction work, 
as conducted in the laboratory from April, 1909, to the winter of 
1909-10, and the dates when the first colonies were planted in the. 
late summer and fall are therein indicated. 
TaBLe I1X.—Results of reproduction work with Schedius. 
. Emergence of prog- 
. 3 eny. Total 
a Number and source of parents. dae es work, | number of | Colo- 
= progeny. nized 
| Began. | Ended. 
Se a es ee es 
First... .- | 11 from imported egg masses..| Apr. 19...........- May 19 | June 14 i?) Bose 
Second...) 114 from first generation. --- .- js |! gaa a June 23} July 16 oS re 
Third. ...| 645 from second generation....| June 23........... July 16 | Aug. 10 aaa 
Fourth...) 1,350 from third generation....| July 16...........- | Aug. 16 | Sept. 7 11, 999 10, 980 
Fifth... .| 1,019 from fourth generation...) Aug. 16...........| Sept. 11 | Sept. 29 6, 286 3, 280 
Sixth...) 3,006 from fifth generation. ....| Sept. 11........... Oct. 5] Oct. 25 12, 723 5, 368 
Seventh...) 7,355 from sixth generation...| Sept. 30..........- Oct. 29 | Nov. 15 35, 423 | 5, 639 
Eighth...| 29,784 from seventh gener- | Oct. 25............].........-|.........- 1 219, 627 20, 115 
ation. 
Ninth....| 199,512 from eighth gener- | Nov. 21-Dec.21.. | eee | 4a eee 1 1,028, 361 733, 967 
ation. 
Tenth....| 294, 400 from ninth generation.| Jan. 5.............|..........).......e. 1 284,779 280, 762 
1 Estimated. 
