248 
PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 
Following these preliminary collections, which were intended for no 
other purpose than to indicate the rate of increase, collections from 
towns and cities to the westward of its known distribution the previ- 
ous winter and to the northward in southern New Hampshire and 
southernmost Maine were made. It was rather confidently expected 
that it would be found in Maine just over the New Hampshire line, 
and also that this would mark the limits of its distribution in that 
direction. 
How far removed the expectations were from the reality is well 
indicated b}^ the accompanying map 1 (PL XXIII) , and still more by a 
study of the table. It will be seen that instead of stopping at the Maine 
State line, Monodontomerus has extended its range for a full hundred 
miles to the northeastward, and that to the north and west it has pretty 
nearly reached the limits of the present known distribution of the 
brown-taii moth itself. But what is more surprising, it is actually 
much more abundant in a large part of this new territory than it was 
in Massachusetts a year before. 
It will also be observed that the distribution has been much more 
rapid toward the north and east than toward the west and south, 
winch is true also of that of the gipsy moth and the brown-tail moth. 
Whether tins will prove to be the rule with others of the parasites 
remains to be seen. It is not indicated in the instance of any other 
as yet. 
Monodontomerus appears to pass through but a single generation 
annually. The females are sometimes, perhaps habitually, fertilized 
before they actually issue from the pupal shell of the host. The 
males invariably die before the winter, or at least out of many thou- 
sands of individuals which have been secured in the winter from 
brown- tail-moth nests at home and abroad, only females have been 
present. Dissection of a considerable number of hibernating females 
has failed to result in the finding of even partially developed eggs. 
Neither has it been found possible to keep females alive in the spring 
until eggs should develop, although some have remained in a state 
of activity in confinement for several months. 
Beginning in 1906, and each year thereafter until 1900, numerous 
attempts wore made to secure reproduction in confinement. Dipter- 
ous larvae and puparia as well as pupae of the gipsy moth and the 
brown-tail moth were supplied as hosts, and females from hibernating 
nests as well as those from gipsy-moth and brown-tail moth pupae 
and other sources were used in these experiments. Failure resulted 
in every instance, due, apparently, to the impossibility of keeping 
the parents alive until eggs should be developed. 
1 The maps and tables have been prepared by Mr. TI. E. Smith, to whom the work of caring for the nests 
us they have been received at the laboratory has largely been intrusted. 
