1907.] PUBLIC DOCUMENT No. 73. 123 



of micro-Hymenoptera. Through Dr. Mayr I learned of the probable 

 importance of certain egg parasites of the brown-tail moth which he him- 

 self had reared in Europe and had described. As the result of this 

 information, egg masses of the brown-tail moth were brought over to 

 Massachusetts in midsummer, and parasites were reared from them by 

 Mr. Titus and were observed to lay their eggs. 



Mr. Titus bred not only the species referred to by Dr. Mayr, namely, 

 Telenomus plialcenorum, which came from eggs forwarded by Miss 

 Riihl and collected in Croatia, but he also reared an apparently un- 

 described parasite of the subfamily Trichogramminae, from egg masses 

 received from Wurtemberg, Dalmatia, and Rhenish Prussia. Both of 

 these species also were observed to lay their eggs in the eggs of the 

 brown-tail moth at North Saugus. 



On the whole, the importations of the spring and the summer were 

 very successful as far as the issuing upon American soil of a number 

 of species of important European parasites is concei'ned. More than 

 fifteen species were reared. Further than this, complete generations 

 of several of the parasites were followed through, and the very im- 

 portant point was determined that the principal parasites reared from 

 the brown-tail moth nests in the early summer would lay their eggs in 

 the larger American brown-tail moth larva? during the summer, and 

 also in the chrysalides of the brown-tail moth and in the larva? of the 

 gypsy moth and the chrysalides of the same species as well; thus pro- 

 viding for the practical carrying through the entire season of parasites 

 found in the wintering nests of the brown-tail moth in Europe, render- 

 ing it possible for the late issuing individuals to attack recently hatched 

 brown-tail moth Iarva3 in August and September, and thus to be car- 

 ried through the winter in the American wintering webs. 



Of the parasites thus reared, I am inclined to base my hopes of 

 success on the species of Pteromalus which we have called P. proces- 

 sioned Ratz., on account of the fact that it is such an abundant 

 European parasite, stinging a number of species of hairy caterpillars, 

 and on account of the further fact that it was bred at North Saugus 

 in such great numbers, it was by far the most abundant species reared 

 from the imported nests. I am also inclined to expect good results from 

 the egg parasites mentioned, although it is too early to predict with any 

 certainty. Among the parasites reared from larvae received during the 

 summer, aside from the Tachina flies, which were the most numerous 

 and which may or may not prove successful, I have the greatest hopes 

 of Pimpla examinator. Although only 150 or 200 specimens of this 

 species were reared, it is an important parasite, and we have as a basis 

 for hope the fact that a congeneric parasite, P. inquisitor, in this coun- 

 try has been found absolutely to wipe out an extensive invasion of the 

 white-marked tussock moth in the city of Washing-ton. 



In my last report to you I referred to the fact that we had been 

 unsuccessful in our efforts to import living specimens of the predatory 



