276 PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



were possible to do so, as the result of the elaborate colonization 

 work already described, and that any harm which might result was 

 probably already done, so it was determined to use these larvae and 

 pupae for the purpose of giving the parasite one more opportunity to 

 retrieve a lost reputation. The brood lived through the summer in 

 cold storage without much loss, and in the fall one tremendous colon}^ 

 of some 200,000 individuals was established in the midst of a tract 

 of small oak, well infested with nests of the brown-tail moth. The 

 adults issued at a time when there was nothing to prevent their 

 entering these nests and ovipositing immediately, and there were 

 enough of them to destroy all of the caterpillars of the brown-tail 

 moth within a considerable radius. There were many larvae to be 

 found in the nests that winter, but, as was the case in the laboratory, 

 only a few of the more exposed caterpillars were attacked. 



A rather elaborate series of nest collections was made within a 

 radius of a mile of the center of the colony, but the data obtained 

 were of little consequence. From only a part of the many lots of 

 nests did any of the parasite issue, and its probable rate of dispersion 

 was not definitely indicated. One lot of nests collected a little over 

 a mile away produced a few individuals, and this was the only 

 instance in which it could be shown to have traveled so far. 



At the same time large collections were made in the vicinity of the 

 1908 colonies, from which, it will be remembered, some few parasites 

 had been recovered the winter before. In no instance was it again 

 recovered, and there was everything to indicate that it had failed 

 to establish itself. 



No attempt whatever was made to rear it for colonization in 1910, 

 and until the beginning of the winter of that year it was considered 

 that the story of Pteromalus in America was complete. It is the 

 unexpected which usually happens in the gipsy-moth parasite labora- 

 tory, however, and even as the rough manuscript for the last few 

 pages was being prepared, Chapter II of the history of Pteromalus 

 egregius in America was about to begin. 



Every winter since that of 1906-7, to and including the present, 

 an increasingly large number of the hibernating nests of the brown- 

 tail moth have been collected from various localities throughout 

 eastern Massachusetts and confined in tube cages in the laboratory. 

 In the first two winters this was done for the express purpose of 

 recovering Pteromalus and, as has been already stated, without 

 result. In the winter of 1908-9, it was found that Monodontomerus 

 was to be recovered in this manner over a considerable territory and 

 under conditions which were both interesting and instructive. 

 Accordingly, beginning with that winter, the collections have been 

 made general throughout the territory in which it was thought likely 

 that Monodontomerus would occur, and with less reference to the 



