132 GYPSY AND BROWN-TAIL MOTHS. [Jan. 



Experiment VII, Elm leaves were smeared with a bacterial cul- 



ture prepared by Dr. George E. Stone from 

 diseased brown-tail moth caterpillars. 



(a) Twenty-five normal gypsy caterpillars were 

 put in a jar with treated leaves. Result : 2 

 caterpillars died. 



(6) Same as (a). Result: 5 caterpillai's died. 



(c) Same as (a). Result: 3 caterpillars died. 



(d) Same as (a). Result: 4 caterpillars died. 

 Experiment VIII. Elm leaves were treated with a mixture of a 



pure culture of the fungous parasite prepared 

 by Dr. Stone. 



(a) Twenty - five gypsy moth caterpillars were 

 placed in a glass jar with treated leaves. 

 Result : 1 caterpillar died. 



Elm leaves treated with pure cultures of Penicillium brevicanle 

 and fed gypsy caterpillars produced scarcely any effect. On 

 account of the lateness of the season, it was impossible to carry on 

 experiments from pure cultures with the brown-tail pupae, and the 

 results of the experiments previously noted should not be con- 

 sidered as conclusive. 



From what is known regarding this group of insect fungi (En- 

 tomophthoreaa), we would expect that, when diseased pupae and 

 diseased caterpillars are brought in contact with healthy ones, infec- 

 tion would result ; and that, when leaves are treated with decoctions 

 of diseased caterpillars and pupae, a certain amount of infection 

 would be likely to take place, since the decoctions would contain 

 the spores of the disease-producing fungus, and if suitable condi- 

 tions for germination and development were at hand infection 

 would follow. 



The condition of the brown-tail pupae found in infested nests 

 also indicates that the disease is infectious, and the association of 

 diseased forms with healthy ones in a breeding case would un- 

 doubtedly produce the same results, providing the conditions were 

 suitable. On the other hand, it might not be improbable that, 

 in selecting what might appear to be healthy pupae and caterpillars 

 for these experiments, some of them were in an incipient stage of 

 disease, which would modify the results. In most instances, how- 

 ever, where death occurred to the pupae or caterpillars in these 

 experiments with brown-tail moths, the characteristic white fungus 

 subsequently appeared. The laboratory, however, being dry and 

 the breeding cases not being closed at the top would give rise to 

 conditions which would have a tendency to check the development 

 of fungi. Undoubtedly the prevalence of rain and damp weather 



