SUMMARY AND CONCLUSIONS. 305 
the brown-tail moth differs from that of the gipsy moth. It further 
differs in that two small gregarious chalcidids, both of them closely 
allied or identical with American species of the. same respective 
genera, have occasionally been reared from imported cocoon masses. 
Neither of these is common. One, Diglochis omnivora Walk, appears 
to be specifically indistinguishable from the form which goes under 
the same name in America, where it has occasionally been reared 
from the gipsy moth and abundantly from the brown-tail moth. 
The other is a species of Pteromalus, which, according to Mr. Craw- 
ford, is hardly to be distinguished from the tussock-moth parasite, 
Pteromalus cuprovdeus How. 
Enough of the latter species have been reared to make small 
colonies possible, but these colonies have been so very small as to 
make its establishment improbable. It is hoped that a larger 
number will be imported in 1911, but since it appears to be of very 
slight importance in Europe no great enthusiasm is felt over the 
prospect. 
SUMMARY AND CONCLUSIONS. 
The work of introducing into America the parasites and other 
natural enemies of the gipsy moth and the brown-tail moth has been 
more arduous than was anticipated when it was begun. It was soon 
found that the published information concerning these enemies was 
deficient and unreliable, and that much original research was neces- 
sary in order that they might be intelligently handled. Later it 
developed that the rate of dispersion of the introduced species was 
so very rapid as to necessitate larger and stronger colonies than had 
been contemplated. 
The policy originally adopted of employing foreign entomologists 
to collect the eggs, caterpillars, and pupz of these pests abroad for 
shipment to the Massachusetts laboratory, where the parasites 
which they contained might be reared, has resulted in the successful 
importation and colonization of a considerable number of the para- 
sites which a study of this material, after its receipt at the laboratory, 
has indicated as being of importance. Numerous others success- 
fully imported have been colonized, but so recently as to render the 
success of the experiment uncertain. On account of the rapidity 
of dispersion, which results in the parasites being very rare Over a 
large territory instead of being common over a restricted territory, 
as long a period as four years may elapse before it is possible to recover 
them after colonization. It has been found impossible to secure cer- 
tain of the parasites in adequate numbers for colonization under satis- 
factory conditions. The proportion of such is very small, it is true, 
but at the same time it may easily be that ultimate success or failure 
95677°—Bull. 91—11—20 
