278 



PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 



much larger colonies will be necessary before we can hope to see that 

 species established in America. To colonize it under more satisfac- 

 tory conditions than those which prevailed in 1909 would be well- 

 nigh impossible except at a very heavy expenditure, because the 

 favorable conditions in 1909 were primarily due to the unusual coinci- 

 dental circumstance of an early season in Japan, and a late season 

 in Massachusetts. Such coincidences can not be depended upon, 

 and without them, a tenfold expenditure over that of 1909 would be 

 insufficient to secure equally favorable conditions for the establish- 

 ment of the species, and a proportionately larger expenditure to 

 better them. 



The story of Pteromalus has been given at length because of the 

 bearing which it has upon the question of what constitutes a satis- 

 factory colony of any species of parasite. Except in a few instances, 

 of which Calosoma and Anastatus are conspicuous, we frankly do 

 not know the answer, and it is only through the study of such phe- 

 nomena as those which have accompanied the recovery of Pteromalus 

 that we are able to judge the probable character of the answer in the 

 instance of those parasites which for some obscure reason or another 

 have failed to make good their establishment in America. 



APANTELES LACTEICOLOR VIER. 



The story has already been told of how, during the winter of 1905-6, 

 some 100,000 hibernating nests of the brown-tail moth were imported, 

 placed in large tube cages in the laboratory at North Saugus, and 

 how some 60,000 Pteromalus and countless thousands of cater- 

 pillars of the brown-tail moth issued into the attached tubes, and 

 were sorted with difficulty. There is not a single published record 

 outside of those emanating from the laboratory, so far as was then 

 known, or is known now, which suggested the possibility of this 

 particular sort of caterpillar harboring other parasites than those 

 which issued as adults from its nests. Mr. Titus recognized that 

 this might well be possible, however, and rather with the purpose 

 of determining the fact than with the expectation of securing such 

 parasites in any quantity for liberation, he caused some of the cater- 

 pillars to be fed in confinement and under observation. His fore- 

 sight was well rewarded when, in the course of time, a number of 

 cocoons of an Apanteles (fig. 67) was found in these cages, and the 

 fact that at least one parasite hibernates within the living caterpillars 

 was demonstrated. 



The following spring he laid his plans for the wholesale rearing of 

 this parasite and whatever other parasites might chance to be present. 

 A considerable number of wood and wire-screen cages (PI. XXVI, fig. 1), 

 modifications of the familiar Riley type, was procured, and as the 

 caterpillars issued from the cages containing the second large importa- 



