72 The American Naturalist. [January, 
7. We have lately ascertained that it may destroy the eggs of the 
chinch bug, and as these are commonly laid where they are kept more 
or less moist, this fact contains a suggestion of increased usefulness and 
a valuable hint as to the best time for introducing the infection into 
the field. 
8. The fungus preducing this disease will not start to grow on dead 
chinch bugs, if we may judge from the results of several experiments 
made this summer. Wherever a dead chinch bug shows its presence, 
consequently, it has made its attack on the living insect. 
9. The resistant power of healthy chinch bugs exposed to infection 
is well shown by the fact that thousands of bugs, young and old, have 
commonly lived for many days, and even for several weeks, moulting, 
maturing, copulating, and laying their eggs, when shut up in infection 
boxes which had been heavily stocked with fungus spores from dead 
insects and had been made in every way as favorable as possible to the 
development of the disease. The percentage of those that would suc- 
cumb from day to day was often ridiculously small. 
10. The growth of the fungus in such boxes is sometimes checked 
and the whole experiment brought to astandstill by the appearance in 
‘the boxes of minute mites (apparently brought in with the food sup- 
plied to the bugs), which multiply in the boxes and greedily devour the 
fungus of white muscardine as fast as it grows. 
11. Comparative experiments with fungus spores from diseased 
chinch bugs and with those derived from artificial cultures on corn 
meal moistened with beef broth, show that the latter are nearly, if not 
quite, as efficient agents of infection as the former. We have used only 
cultivated spores one or two removes from the growth on the insect, 
and consequently are not prepared to say that continued cultivation on 
an inanimate medium might not finally diminish the virulence of the 
fungus parasite ; but, on the other hand, we have no very good reason 
to suppose that this will prove to be the case. I have no doubt, how- 
ever, that by a properly guarded procedure, these artificial cultures, 
which can easily be made in almost unlimited quantity, may be util- 
ized for a dissemination of the spores of these insect diseases, with 
great advantage in convenience, expedition, and economy of opera- 
tion, 
From all our experimental work thus far completed, I draw the gen- 
eral conclusion that infection with the fungus of the white muscardine 
of the chinch bug is an uncertain measure, largely dependent-for its 
practical value upon conditions beyond the inftuence of the experi- 
menter, and whose occurrence or prevalence it is impossible for him to 
