Siath Annual Report. 33 
FINAL SUMMARY. 
RESULTS OF EXPERIMENTS FOR TEN YEARS —1888-1897. 
1. Chinch-bugs in any of their stages of development scarcely 
run the slightest risk of death on account of heavy rains, even 
__ when these are of long duration. They are inconsiderably af- 
fected by extremes of heat and cold. 
Notr.— When chinch-bugs cross en masse a hot, dusty road-bed, the many 
that die are killed by the particles of dust that enter their spiracles rather tha 
_by the heat. 
2. We know of no contagious bacterial disease of the chinch- 
bug. | 
38. There are two parasitic, contagious, fungoid diseases that 
kill chinch-bugs, namely : Sporotrichum globuliferwm (the ‘‘ white 
_fungus’’), and Empusa aphidis (the ‘‘ gray fungus’’). 
Note.— Our experiments have to do mainly with the white fungus, as it is 
better understood and controlled than is the other. 
4. These two diseases show their greatest virulence where the 
ground is damp and shaded from the direct rays of the sun and 
the air is humid. 
5. We do not know to what extent the spores of these diseases 
are normally present in any given region. When they are pres- 
ent, whether naturally or artificially introduced, and the weather 
conditions are as given above, and the bugs are massed together, 
an outbreak of the disease will occur. The number of chinch- 
bugs killed in any field is approximately proportionate to the 
number of bugs in the field. 
Norz.—It is as true of the bugs as it is of ourselves, that the number of indi- 
viduals carried away by a plague is dependent upon various conditions, such as 
those of weather, nourishment, density of population, etc. 
6. Sporotrichum can be artificially communicated to healthy 
chinch-bugs. (qa) It attacks bugs of all ages, but the older the 
bug the more easily does it succumb. (b) Bugs of any age 
- that have been weakened from any cause, or injured, fall more 
easy victims to the disease than do those individuals that are 
in perfect condition. (c) The adults of the second brood, 
which in the ordinary course of events winter over and lay the 
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