INFLUENCE OF PRECIPITATION ON CHINCH BUG. 43 
which may be composed of leaves and dried grass, may be burned away 
in early winter and thus leave the insects without the expected protec- 
tive covering, 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 temperature, and the latter then 
becomes a factor of secondary importance in the problem of life among 
chinch bugs. It is very doubtful if temperature is as vital in its ef- 
fects as are the indirect influences of precipitation during the breeding 
season. 
It has long been understood that the two species of entomogenous 
fungi, Sporotrichum globuliferum Speg. and Entomophthora aphidis 
Hoifm., 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 becomes sufficiently abundant to cause 
any serious mortality among the insect host, but this matter will 
receive attention in the discussion of these parasitic foes farther on. 
INFLUENCE OF TEMPERATURE ON THE CHINCH BUG. 
The writer would call attention here to a possible influence of 
temperature upon what he has termed the west-bound tide of migra- 
tion. When the time arrives for the hibernating adults to leave 
their winter quarters and disperse over the fields prior to oviposition, 
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 attention to the influence which this phenomenon exerts 
upon the chinch bug. Now, this retardation amounts probably to 
about a month in spring, which would have a tendency to delay ovi- 
position, especially among the short-winged females. If this were 
continued through a long period of time, consequent upon the slow 
movement of this 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 habita- 
tion along the shores of the northern Atlantic would be to some extent 
encouraged by the prolonged northern winter and the correspond- 
ingly shorter period during which the species could breed, and thus 
instead of the effects of the old environment becoming obliterated 
they might be continued, or, as in case of the fore-shortening of the 
wings, still further intensified. If the effect of this prolonged period 
a Insect Life, Vol. VII, p. 422. 
