56 
ion to beer mash as a cultivating fluid. If one boils a little of this 
n a flask, and, after cooling, sows it with spores, a rich mycelium 
levelops, both within the fluid and upon its surface, and this pro- 
luces the spores again. To guard against the invasion of other 
ungi, which will ordinarily suppress the Isaria growing outside the 
)ody of the insect, the flask must be stopped with a little disinfected 
jotton or asbestos.” 
By Dr. Sliimer, the enormous destruction of chinch-bugs in 1:66 
vas ascribed to the indirect effect of the wet and cool weather. By 
VIr. Walsh, who discredited the idea of an epidemic or contagious 
lisease, it was accounted for as the direct effect of moisture.* The 
phenomena connected with the action of parasites, which I have above 
lescribed, were apparenty independent of any appreciable general 
»ause, as they were most manifest at a time when the weather had 
)een warm, dry, and altogether unexceptionable for from one to two 
nonths. It is not unlikely, however, that wet weather may have the 
)ffect to stimulate the development of this parasite, either directly 
>r indirectly—a hypothesis which will reconcile all the facts now 
mown, as well as the conflicting explanations of them which have 
>een hitherto put forth. 
The most important facts under the head of natural enemies may 
>e thus recapitulated: 
The chinch-bug is subject to attack by all the common lady-bugs 
Coccinellidce) and their larvge, by a common predaceous ground 
)eetle ( Agonoderus comma), by the larva of the lace-wing fly, and 
>y one of the robber-bugs ( Harpactor cinctus ). A number of Cocci- 
lellidce, however, captured among the chinch-bugs, were shown by 
lissection to have taken only about eight per cent, of their food 
rom these insects, the remainder consisting of plant-lice, spores of 
nolds and lichens, and the pollen of flowering plants; .while the 
predaceous ground-beetle mentioned (. Agonoderus ) was found to have 
lerived about one-fifth of its food from the bugs, and the remainder 
partly from other insects, but chiefly from the tissues of ordinary 
olants. A few common birds are shown to feed upon chinch-bugs 
pccasionally. The joint effect of these various ordinary enemies is 
not necessarily insignificant, but is certainly of no great present 
importance. 
On the other hand, a much more important role is apparently 
played by certain obscure parasites, not previously detected. One 
of these is a minute bacterium ( Micrococcus insectorum, Burrill,) in¬ 
festing the alimentary canal, closely allied to the micrococcus found 
in the stomach and intestines of silk-worms, and now known to 
pause 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 ad¬ 
jacent fields there were relatively very few, it was considered prob- 
*American Entomologist, Vol. I, p. 175,1869. 
