93 
cording to our observations, to have much more to do with tho 
appearance and spread of the white muscardine among chinch-bugs 
than even the most persistent distribution of dead or infected 
specimens in the absence of such natural culture beds—a fact 
which contains the suggestion of a new method for the propaga¬ 
tion and dissemination of this disease. It will be well worth 
while, consequently, to try the effect of excessive moisture and 
an inviting shelter on here and there a spot in an infested field,, 
such as might be afforded by an overgrowth of small grain pro¬ 
duced by heavy fertilization, or by tramping down a few hills of 
corn, or by the early cutting and shocking of some small part of the 
crop. If no spontaneous development of muscardine were to follow, 
such spots would at any rate be excellent places to start a field 
infection. 
3. If decidedly wet weather follows upon its introduction, even 
after an interval of several weeks, it is likely to start up and 
take visible effect; but continuous rains, depressing the vital ener¬ 
gies of the insect, seem commonly requisite to its efficient action. 
(See Nos. 55 to 58, 77, etc.) 
4. It is always so generally prevalent, in a more or less obscure 
condition, among chinch-bugs or other insects in Illinois, both 
north and south, that it is very like to appear and spread, as if 
spontaneously, whenever conditions favorable to its development 
long prevail, whether it has been purposely introduced or not. 
(See especially No. 76.) 
5. The time elapsing between the establishment of such favor¬ 
able conditions and the full development of the disease among the 
chinch-bugs of any locality, may possibly be shortened if the in¬ 
fection has previously been introduced by artificial means; but 
our own experiments, it must be confessed, do not lend any materi¬ 
al support to this supposition. (See No. 57, concluding discussion.} 
6. Whatever weakens the insect favors its spread, as a rule. It 
is consequently much more likely to attack adults than young, 
especially spent males, and females which have laid their eggs 
and are soon to die of old age; but it nevertheless kills 
young of all ages. From the record of our large contagion boxes 
(Nos. 68-71) it appears that after the establishment in my labo¬ 
ratory, Jaly 1, of a special reception box into which all insects 
sent in by mail or express were put as received, the development 
of the fungus in the contagion boxes was much less rapid than 
before. The reception box was so managed that not only were 
all dead bugs excluded from the contagion boxes, but only the 
more vigorous of those remaining alive at the time of their arrival 
were transferred, The apparent effect of this elimination of weak¬ 
ened insects was greatly to diminish the number which succumbed 
to the muscardine infection. 
In agreement with the above, we have noticed that the fall gen¬ 
eration of adults is less subject to it, other things being equal, 
than the generation which matures in midsummer. As this fall 
brood is to live over winter before laying its eggs, it contains no 
worn-out adults. 
