38 THE CHINCH BUG. 
effect on this species. As previously shown, the temperature effects 
are, largely at least, unfavorable for such adults as may happen to be 
more or less unprotected during the hibernatiug season. Upon this 
point it might be well to suggest that this protection, which may be 
composed of leaves and dried grass, may be burned away in early 
winter and thus leave the insects without the expected protective cov- 
ering, or this covering may be still further augmented by a mantle of 
snow, which, remaining for a more or less protracted period of time, 
counteracts the influences of temi)erature, and the latter then becomes 
a factor of secondary importance in the problem of life among chinch 
ougs. It is very doubtful if temperature is as vital in its effects as are 
the indirect influences of precipitation during the breeding season. 
It has long been understood that the two species of entomogenous 
fungi, Sporotrichium globuliferum Speg. and Untomophthora aphidis 
Hoffm., both of which attack the chinch bug, require for their rapid 
development an atmosphere heavily charged with moisture, and that 
without this neither of these become sufficiently abundant to cause any 
serious mortality among the insect host, but this matter will receive 
attention in the discussion of these parasitic foes further on. 
INFLUENCE OF TEMPERATURE ON THE CHINCH BUG. 
I would like to call attention here to what seems to me a possible 
influence of temperature upon what I have termed the west-bound tide 
of migration. When the time arrives for the hibernating adults to 
leave their winter quarters and disperse over the fields prior to oviposi- 
tion, if the weather should prove too severe they have but to remain in 
these quarters a while longer until more favorable weather. Thus along 
the northern Atlantic coast the season is generally much later near the 
shore than it is a few miles inland, and Mr. Schwarz* has called atten- 
tion to the influence which this phenomenon exerts upon the chinch 
bug. Now, this retardation amounts to about a month in spring, I 
believe, which would have a tendency to delay oviposition, especially 
among the short-winged females. If this were continued through a 
long period of time, consequent upon the slow movement of tbis tide 
of migration northward along the coast, it would hardly be surprising 
to find that this retarded activity in spring had become so characteristic 
as to be retained after this tide had swept to the westward, and resulted 
in the species being thus single brooded in the East, while it is double 
brooded in the east-bound tide of migration in the West. This effect of 
a long habitation along the shores of the northern Atlantic would be to 
some extent encouraged by the prolonged northern winter and the 
correspondingly shorter period during which the species could breed, 
and thus instead of the effects of the old environment becoming oblit- 
erated they might be continued, or, as in case of the fore-shortening 
of the wings, still further intensified. If the effect of this prolonged 
* Insect Life, Vol. VII, p. 422. 
