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 soon 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 IX. — Results of reproduction work with Schedius. 



Gener- 

 ation. 



Number and source of parents. 



Reproduction work 

 begun. 



Emergence of prog- 

 eny. 



Total 

 number of 

 progeny. 



Colo- 

 nized. 



Began. 



Ended. 



First 



11 from imported egg masses. . 



114 from first generation 



645 from second generation 



1,350 from third generation 



1,019 from fourth generation. . . 



3,006 from fifth generation 



7,355 from sixth generation.. . 



29,784 from seventh gener- 

 ation. 



199,512 from eighth gener- 

 ation. 



294, 400 from ninth generation. 



Apr. 19 



May 19 

 June 23 

 July 16 

 Aug. 16 

 Sept. 11 

 Oct. 5 

 Oct. 29 



June 14 

 July 16 

 Aug. 10 

 Sept. 7 

 Sept. 29 

 Oct. 25 

 Nov. 15 



114 



645 



1,350 



11,999 



6,286 



12, 723 



35,423 



1219,627 



11,028,361 



i 284, 779 





Second. . . 



May 19 





Third.... 



June 23 





Fourth... 



July 16 



10, 980 



Fifth 



Aug. 16 



3,280 

 5,368 



Sixth 



Sept. 11 



Seventh. . 



Sept. 30 



5,639 



Eighth... 



Oct. 25 



20, 115 



Ninth.... 



Nov.21-Dec.21. .. 







733, 967 



Tenth. . . . 



Jan. 5 







280, 762 













i Estimated. 



