280 



Mycologia 



these were in a nest which had been previously sprayed with a 

 suspension of spores in sterile water. Thus the fungus cannot be 

 classed as of economic importance since it is only at the higher 

 temperatures that it does its damage. 



These conditions suggested a series of experiments to try out 

 the possibility of artificial infection at the normal and higher 

 temperatures. 



Six larvae from a perfectly normal nest together with a sufficient 

 number of wild cherry leaves for food, were put into each of 

 four sterile bottles, two of which were sprayed with a spore sus- 

 pension and the other two kept as a check. The bottles were 



Fig. I. Section through the cuticle of Malacosoma americana Fabr. show- 

 ing the penetration of Aspergillus flavescens Eidam to the exterior through 

 the region of a dermal pore, and the presence of the fungus in the inner layer 

 of the chitin. X 400. 



plugged with sterile cotton and placed in the same compartment 

 of an incubator maintained at a temperature of about 37° C. A 

 similar experiment was conducted at the normal outdoor tempera- 

 ture (2i°-27° C). At the end of three days all of the larvae 

 in the sprayed bottle kept in the incubator were dead from in- 

 fection with Aspergillus flavescens. The control specimens, at 

 the incubator temperature, showed no signs of such infection. In 

 the case of the experiment conducted at outdoor temperature, 

 none of the larvae, either sprayed or unsprayed, showed any signs 

 of such infection. A second series of these experiments was car- 

 ried on with the same results as the first. 



