44 THE CHINCH BUG. 
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 abun- 
dance 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 meteorological conditions act as natural checks. Al, doubt- 
less, have other host insects, and the two most important have been 
known to break out again and again spontaneously and destroy myr- 
iads of chinch bugs when the latter were present in excessive numbers. 
But this has taken place only in connection with the necessary pre- 
cipitation; hence these fungi become natural enemies only under 
certain favorable weather conditions; and though their season of 
most potent effect is during the time when the chinch bug is develop- 
ing 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 L'ntomophthora aphidis Hoffman * and Sporotrichum 
globuliferum Speg,’ both having probably been associated in destroy- 
ing the chinch bug spontaneously in 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 effects 
of the two in the earlier literature, even the first observations of Dr. 
Henry Shimer“ probably applying to their joint effect. 
« Hoffman, in Fresenius’s “ Entomophthorew,” p, 208, figs. 59-67, 
»b Spegazzini, ‘Fungi Argentini,” II, p. 42. 
¢ Proc. Acad. Nat. Sci. Phila., May, 1867. 
