NATURAL ENEMIES. 39 
period of hibernation has been to reduce the number of broods, then it 
will have to be considered as a natural check, in that to a certain extent 
it prevents excessive abundance by reducing the number of offspring. 
This would also account for the rather surprising immunity that has 
heretofore been enjoyed by the northeastern portion of the country 
from the ravages of this destructive species. 
NATURAL ENEMIES. 
It is possible that there are some reasons which might appear to 
justify the placing of fungous enemies of the chinch bug among the 
natural checks, as they no doubt do exert a more or less powerful 
influence in that direction, but it seems more convenient to include 
them among natural enemies, especially as one at least has come to be 
applied artificially to overcome the insect. The fact that the abundance. 
and consequent influence, of these fungous enemies is almost entirely 
dependent upon meteorological conditions is sufficient to place them in 
a secondary position, even though they may under favorable meteor- 
ological conditions act as natural checks. All. doubtless, have other 
host insects, and the two most important have been known to break 
out again and again spontaneously and destroy myriads of chinch 
bugs when the latter were present in excessive numbers. But this has 
taken place only in connection with the necessary precipitation; hence 
these fungi become natural enemies only under certain favorable weather 
conditions; and while their season of most potent effect is during the 
time when the chinch bug is developing from the egg to the adult, yet as 
shown by observation they may exert powerful and fatal effects among 
the adults, where these last have congregated together in masses. 
PARASITIC FUNGI. 
The two species of entomogenous fungi to which reference has just 
been made are Entomophthora aphidis Hoffman * and Sporotriehium 
globuliferum Speg,f both having probably been associated in destroy- 
ing the chinch bug spontaneously m the fields, and doubtless were 
distributed to correspondents by Professor Snow and others to be 
artificially established in fields where there was an overabundance of 
chinch bugs. For this reason it is impossible to separate the two. even 
the first observations of Dr. Henry Shinier f probably applying to their 
joint effect. 
Dr. Shinier, however, was the first to call attention to the widespread 
and fatal effects of fungous diseases among chinch bugs, and while his 
explanations therefor seem now crude and illogical, his observations 
were made with such care and accuracy that we have not yet had occa- 
sion to materially revise them, though his conclusions have been shown 
"Hoffman, in Fresenius's "EntomophthoresB," p. 208, tigs. 59-67. 
* Spegazzini, " Fungi Axgentini," II. p. L2. 
fProo. Acad. Nat. Sci. Phila.. May, 1867. 
