45 
It is very evident that the effect of the enemies thus far noted, 
upon an insect as numerous and extraordinarily prolific as the 
chinch-bug, cannot be very great. Unless they should, under special 
circumstances, become much more abundant than they have ever 
yet been found, they could certainly, even under the most favorable 
conditions, contribute little to the protection of the farmers’ crops. 
Parasites. 
I come now, however, to a class of enemies which have hitherto 
eluded observation, but which, if they fulfil! in future the promise 
which our present knowledge of them indicates, should be among 
the most destructive enemies known to insect life. 
No class of diseases-is more fatal to man or more dreaded and 
destructive among the domestic animals than the contagious diseases, 
which are propagated from one individual to another by means of 
some infinitesimal virus. When we remember that not only man 
himself, but also nearly or quite every animal with whose economy 
we are fully acquainted, suffers at times immense destruction from 
diseases of this character, falls a victim, in other words, to micro- 
scopic enemies, we may indulge a reasonable hope that tiose 
insects less known to us, but many of them scarcely less important, 
are not altogether free from them; and when we reflect that the 
number of horses or hogs or chickens could easily be vastly reduced 
by using a little ingenuity to spread broadcast the germs of their 
contagious diseases, we need not despair of effecting something in 
the same direction among our most noxious insect enemies. 
We are not without several indications that contagious or epi- 
demic diseases of this nature occur among them at more or less 
frequent intervals, and, fortunately, we have conclusive evidence of 
the possibility of propagating such diseases artificially. The earlhest 
suggestion of the artificial cultivation of fungus parasites with a 
view to their use for controlling insect ravagés is, as far as I know, 
that of Dr. J. L. Leconte, made in a paper read before the Ameri- 
ean Association for the Advancement of Science, in August, 1873, 
where, in enumerating the checks available for the suppression of 
insects, he mentions the “communication of fungoid disease (like 
pébrine, which affects the silk-worm) to other lepidopterous larve,” 
and adds in a foot-note: ‘‘I am extremely hopeful of the result of 
using this method. I have learned of an instance in which, from 
the communication of the disease by some silk-worms, the whole of 
the caterpillars in a nine-acre piece of woods were destroyed.” 
The first description of anything resembling an epidemic or con- 
-tagious disease among chinch-bugs, we owe to Dr. Henry A. Shimer, 
of Mt. Carroll, Ill., who published a paper setting forth his obser- 
vations upon this imsect, in the proceedings of the Academy of 
Natural Science of Philadelphia, for 1867. On pages 78-80 of that 
volume, he remarks as follows: 
“July 16.—A farmer four miles from here informed me that a 
black coleopterous insect was destroying the chinch-bugs on his 
farm very rapidly; and, although I found his supposition to be an 
error, yet I found many dying on the low creek bottom land from 
