THE CHINCH BUG. 
27 
northern part of the valley of the Mississippi, outnumbering all the human beings 
that have ever lived on this planet siuce the morning of creation. 
This disease among the chinch bugs was associated with the loug-continued wet, 
cloudy, cold weather that prevailed during a greater portion of the period of their 
development, and doubtless was in a measure produced by deficient light, heat, aud 
electricity, combined with excessive humidity of the atmosphere, whereby an imper- 
fect physical (“ bug”) organization was developed. The disease was at its maximum 
during the moist weather that followed the cold rains of June and the first part of 
July. The young chinch bug spent a great portion of its time on or near the ground, 
where its body was colder than the atmosphere; hence, upon philosophical principles, 
there must have been an excessive precipitation of watery vapor in the bronchial 
tubes. These are the facts in the case, but in the midst of the great obscurity that 
envelops epidemic diseases among men, it would be only idle speculation to attempt 
to define the cause more definitely than the physiological laws already observed seem 
to indicate. At all events it will require many years of warm, dry summers, and ac- 
companying winters of plenty of snow for protection, to reinstate the lost innumera- 
ble armies of this insect. 
During the summer of 1866 the chinch bugs were very scarce in all the early spring, 
and up to near the harvest I was not able, with the most diligent search, to find one. 
At harvest I did succeed in finding a few in some localities. 
Professor Forbes took up the study of the Chinch Bug Disease iu Au- 
gust, 1882 , aud has published several interesting accounts of his results. 
A short summary was published in his first report as State Entomolo- 
gist of Illinois, for the year 1882 , of the long account of his studies and 
experiments, and it is in such shape that we reproduce it here: 
On the other hand, a much more important role is apparently played by certain ob- 
scure parasites, not previously detected. One of these is a minute bacterium ( Micro- 
coccus insectorum, Burrill), infesting the alimentary canal, closely allied to the micro- 
coccus found in the stomach and intestines of silk-worms, and now known to cause 
some of the destructive diseases of that insect. From the fact that these parasites 
were extremely abundant in specimens from a field where the bugs were rapidly dying, 
while in those from adjacent fields there were relatively very few, it was considered 
probable that they were related to this destruction of the bugs. This conclusion was 
supported by the factthat they were more abundant in old bugs than in young, while 
the mortality referred to evidently also chiefly affected the older individuals. It was 
found easy to cultivate the bacterium artificially in organic infusions, but no oppor- 
tunity offered to apply it to healthy insects. Until this experiment is made and the 
effects carefully studied, it must remain possible that the coincidence noted was 
merely accidental, and of no particular significance. 
Another parasite discovered is similar to that well known as a common enemy of 
the house fly, and belongs to the same genus ( Entomophthora ). This attacks both old 
aud young chinch bngs, and finally embeds their bodies in a mass of mold. There is 
some reason to believe that this was the active agent in an immense destruction of 
chinch bugs which occurred in Northern Illinois in 1866, as described by Dr. Shimer, 
of Mount Carroll. Evidence is adduced of the possibility of artificially cultivating 
this parasite also, and applying it to the destruction of insects. 
Since the publication of this report Professor Forbes has taken up 
the study of bacterial diseases of certain other insects, but there has 
been, so far as we are aware, no practical outcome as yet. The subject, 
however, has a rather hopeful look, although we should be inclined 
to expect more from the Micrococcus than from the Entomophthora. The 
evidence mentioned as to the possibility of artificially cultivating the 
