72 GYPSY AND BROWN-TAIL MOTHS. [Jan. 



ing the latter upon lettuce and other hothouse foliage, and in the early 

 spring securing more normal food for them by sending it up in boxes 

 by mail from "Washington and points south. In this way the breeding 

 of the parasites of the genus Pteromalus was carried forward unin- 

 terruptedly throughout the winter, and, 'as during the breeding of suc- 

 cessive generations they multiplied exceedingly, it was possible later 

 in the year to liberate a vastly greater number of individuals than 

 would have been possible had the imported species been allowed to 

 hibernate normally in the nests. In the course of this work Mr. W. 

 F. riske, in charge of the breeding operations, has invented a rearing 

 tray which has been of the utmost advantage, and which will greatly 

 facilitate parasite rearing work in the future. 



Still a fifth innovation, and one of great value, has been the dis- 

 covery and practice of retarding the development of brown-tail moth 

 eggs by keeping them in cold storage until the arrival of the European 

 egg parasites, which will oviposit upon and breed in these cold-storage 

 eggs as freely as in those which they attack in the state of nature. 

 This process, it has been ascertained, may be carried on for a long 

 time, and successive generations of these egg parasites may be reared 

 from eggs retarded in their development by cold storage. It is thus 

 easy to breed and to liberate an almost infinitely greater number of 

 these egg parasites, and under favorable conditions, than would be 

 possible from a simple importation of European parasitized eggs 

 which would have to arrive in America at a specific time. These latter 

 innovations have been due to the ingenuity of Mr. Fiske. 



In the same way great advance has been made in the rearing of the 

 Tachinid parasites, under the charge of Mr. C. H. T. Townsend, who 

 has devised methods and made observations that have greatly added 

 to our knowledge of the biology of these insects, and have resulted 

 in the accumulation of a store of information of the greatest practical 

 value not only in the prosecution of the present undertaking, but in 

 any problem of parasite introduction or control that may arise later. 

 Extraordinary and almost revolutionary discoveries have been made in 

 the life histories of certain of these flies, and without this knowledge 

 the greatest success in handling them practically could not have been 

 reached. 



Similarly, Mr. A. F. Burgess, in charge of the Coleoptera, has suc- 

 ceeded in a very perfect way in rearing and liberating the important 

 European predatory beetle (Calosoma sycophanta) , as well as some 

 other insects of the same family. 



Altogether, down to July 1, 1908, the following material was im- 

 ported : — 



Brown-tail moth egg masses, about 26,000. 



Hibernating nests of the brown-tail moth, from 50,000 to 60,000. 



Free larvae and pupse of the brown-tail moth, about 178,000. 



Gypsy moth egg masses, 7 boxes, each containing very many masses. 



