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 
t his parasite and whatever other parasites might chance to be present. 
A considerable aumberof wood mid 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- 
