45 
I : 
! ^ is very evident that the effect of the enemies thus far noted, 
pon an insect as numerous and extraordinarily prolific as the 
hmch-bug, cannot be very great. Unless they should, under special 
lrcumstances, become much more abundant than they have ever 
et been found, they could certainly, even under the most favorable 
onditions, contribute little to the protection of the farmers’ crops 
If.-' * 
I come now, however, to a class of enemies which have hitherto 
luded observation, but which, if they fulfill in future the promise 
duch our present knowledge of them indicates, should be among 
be most destructive enemies known to insect life. 
No class of diseases is more fatal to man or more dreaded and 
estructive among the domestic animals than the contagions diseases , 
diich are propagated from one individual to another* by means of 
ome infinitesimal virus. When we remember that not only man 
imself, but also nearly or quite every animal with whose economy 
r e are fully acquainted, suffers at times immense destruction from 
iseases of this character, falls a victim, in other words, to rnicro- 
3opic enemies, we may indulge a reasonable hope that those 
lsects less known to us, but many of them scarcely less important, 
re not altogether free from them; and when we reflect that the 
umber of horses or hogs or chickens could easily be vastly reduced 
y using a little ingenuity to spread broadcast the germs of their 
ontagious diseases, we need not despair of effecting something in 
le same direction among our most noxious insect enemies. 
TVe are not without several indications that contagious or epi¬ 
demic diseases of this nature occur among them at more or less 
sequent intervals, and, fortunately, we have conclusive evidence of 
pe possibility of propagating such diseases artificially. The earliest 
^ggestion of the artificial cultivation of fungus parasites with a 
iew to their use for controlling insect ravages is, as far as I know, 
lat of Dr. J. L. Leconte, made in a paper read before the Ameri- 
an Association for the Advancement of Science, in August, 1873, 
here, in enumerating the checks available for the suppression of 
lsects, he mentions the “communication of fungoid disease (like 
rebrine, which affects the silk-worm) to other lepidopterous larvae,” 
nd adds in a foot-note: “I am extremely hopeful of the result of 
sing this method. I have learned of an instance in which, from 
ie communication of the disease by some silk-worms, the whole of 
le caterpillars in a nine-acre piece of woods were destroyed.” 
f The first description of anything resembling an epidemic or con- 
igious disease among chinch-bugs, we owe to Dr. Henry A. Shinier, 
d Mt. Carroll, Ill., who published a paper setting forth his obser¬ 
vations upon this insect, in the proceedings of the Academy of 
atural Science of Philadelphia, for 1867. On pages 78-80 of that 
ilume, he remarks as follows: 
i “*Tuly 16.—A farmer four miles from here informed me that a 
lack coleopterous insect was destroying the chinch-bugs on his 
irm very rapidly; and, although I found his supposition to be an 
:ror, yet I found many dying on the low creek bottom land from 
