CHINCH BUG WEST OF MISSISSIPPI RIVER. 



47 



in these cages, thus eliminating that source of infection. This indi- 

 cates that the spores of the fungus were present on the bodies of the 

 living bugs and were only awaiting favorable conditions for germi- 

 nation and abundant growth. In all such cage experiments the fungus 

 appeared only on the bodies of the chinch bugs that had died in the 

 cages and were lying on the soil. 



In the experiments at Washington, D. C, it was desired to obtain 

 a better knowledge of this fungus and its relation to dead bugs, in 

 order to ascertain to what extent, if any, it will grow saprophytically 

 upon their dead bodies. Also to observe the rate of mortality among 

 live chinch bugs, placed in cages and artificially inoculated, as com- 

 pared with those under sim- 

 ilar cage conditions not so 

 inoculated. In the artifi- 

 cial inoculation, the fungus 

 was applied by thoroughly 

 dusting the bugs with the 

 spores of the fungus by 

 means of a small brush, or 

 in other cases by shaking 

 them about in a vial con- 

 taining the fungus-covered 

 chinch bugs. 



Experiments with 



DEAD CHINCH BUGS. To 



determine whether or not 

 Sjwrotrichum globuliferum would make its entire growth upon the 

 dead bodies of chinch bugs, a large number of live bugs, collected 

 from tufts of Androjwgon scoparius, and winch died while confined in 

 a vial, were inoculated artificially and their bodies placed on moist 

 blotting paper. The results of these artificial inoculations compared 

 with their checks are here given. 



Inoculation experiments with dead bugs. 



Fig. 15.— The chinch bug: Adults covered with "white 

 fungus" (Sporotrichumglnbt(liferum). Enlarged. (Origi- 

 nal.) 



Artificially inoculated. 



Checks. 



Number 

 bugs used. 



Number 



developing 



fungus. 



Per cent 



which 



developed 



fungus. 



Number 

 bugs used. 



Number 



developing 



fungus. 



Per cent 



which 



developed 



fungus. 



25 

 25 

 25 

 25 

 40 



5 

 1 



5 



4 



' 5 



20 

 4 

 20 

 16 

 12 



100 



200 

 25 

 25 

 25 

 40 



2 

 2 

 

 2 

 

 



2 

 1 



8 







140 



20 



14.28 



415 



6 



1.45 



