100 
PARASITES OF GIPSY AND BROWN-TAIL MOTHS. 
the stripped trees to others in the vicinity, and it is an unmistakable 
fact that such migrations, which have several times been mentioned 
in the earlier reports of the State superintendent of moth work, are 
now decidedly less frequent, even without taking into consideration 
the greater territory throughout which the moth is now present in 
destructive abundance. Although the junior author has personally 
visited large numbers of outlying colonies of the moth in the course 
of 1908, 1909, and 1910, he has yet to see one in which the disease 
had not appeared coincidently with the development of the colony 
to the stripping stage, if not slightly in advance of that time. 
It is probably safe to say that such conditions as are described in 
the first annual report of the superintendent of moth work as pre- 
vailing over a large territory in the old infested section during 1904 
and 1905, will probably not immediately recur in the history of the 
gipsy moth in eastern Massachusetts. That something approaching 
this may result in parts of New Hampshire is well within the bounds 
of probability, and that the conditions will be very bad in that State 
during the course of the next few years as well as in some of the 
towns in Massachusetts may be accepted as most probable. What- 
ever may be the condition presented by the older infested sections 
in eastern Massachusetts five or ten years from now, the only hope 
of preventing an ever-increasing wave of destruction from spreading 
over western Massachusetts, across New Hampshire and Vermont, 
and over the border into the State of New York, seems to lie, as 
always, in an increasing expenditure for hand suppression or in the 
success of the experiment in parasite introduction. Through the 
methods now in operation it is probable that the pest will very largely 
be prevented from making long " jumps," which would otherwise 
have been of frequent occurrence, but the slower and more steady 
natural spread, through the agency of wind, and probably, when the 
headwaters of the Connecticut, Hudson, and Ohio are reached, by 
water, must be considered in every attempt to discount the future. 
It was taken into consideration when the future of the parasite work 
was decided upon. 
In the course of the studies of the parasites and parasitism of native 
insects which have been undertaken in connection with those of the para- 
si tes of the gipsy moth and the brown-tail moth, no less than three spe- 
cies have been encountered which are controlled to some extent by a 
disease which bears a very close superficial resemblance to the "wilt" 
of the gipsy moth. These are the white-marked tussock moth, the 
tent caterpillar, and the "pine tussock moth." 
The white-marked tussock moth (Hemerocampa leucostigma S. & A.) 
is well known as a defoliating pest in cities, and has been so abundant 
as at times to become a rival of the gipsy moth in its destructive 
capacities in certain of the larger cities in southeastern New England. 
