NUMBER OF ANNUAL GENERATIONS. 23 
on the part of the pupa- to secrete themselves while transforming to 
adults does not at all coincide with the idea of a supposed immunity 
from attacks of uatural enemies. Surely our species of Blissus has not 
always lived where natural enemies were as few as they are with us at 
the present time. Even where we have both the long-winged and 
short- winged forms occurring together in timothy meadows, then- is 
no such haste exhibited on the part of the former to escape from the 
companionship of the latter, as observed by Professor Sajd. We know. 
however, that our species certainly does enjoy a considerable immunity 
from natural enemies, though its conspicuous colors in both the larval and 
adult stages contrast very strongly with those of its usual food plants 
and its presence is still further advertised by its strangely persistent 
gregarious habits. We have come to suppose the species to be. in part 
at least, protected from attack by its vile odor, and so, indeed, it may 
be in the United States, but I fully believe that somewhere in its south- 
ern habitat it will be found to have one or more enemies, like the ant, 
Eciton hamata, of Central America, for illustration. Our native ants, 
however, will seldom attack even the young. 
NUMBER OF ANNUAL GENERATIONS. 
Over the most of its area of habitation in North America, at least, the 
chinch bug is two brooded, though in northeastern Ohio I have totally 
failed to detect the second brood, or, in fact, to perceive any indica- 
tions that a second brood occurs ; but to this I shall refer later. As 
previously shown, there is not sufficient proof at hand to warrant the 
statement that there is even in the far South a partial third brood. 
I believe that the number of annual broods of this species has been 
primarily decided in its home in the tropical regions by the wet and 
dry seasons occurring there, and that we have in the North these same 
broods occurring at slightly different periods under the influence of a 
change from wet and dry to hot and cold seasons. 
Belt, in his Naturalist in Nicaragua, has the following to say with 
regard to the seasons on the northeastern side of that country: -*The 
rains set in in May and continue with occasional intermissions until 
the following January, when the dry season of a little more than three 
months begins" (p. 103). "The heaviest rains tall in July and August. 
and at those times the brooks are greatly swollen." " In September. 
October, and November there are breaks of tine weather, sometimes 
lasting for a fortnight, but December is generally a very wet month, 
the rains extending far into January, so that it is not until February 
that the roads begin to dry up" (p. 104 . It seems that we here have 
the possible key to the secret of the number of annual broods of the 
chinch bug. That it may be able to adapt itself still further to changed 
latitude and environments and become single brooded is not at all 
impossible. As illustrating the ease with which insects, at least some 
of them, can change their habits to correspond with their environment. 
