55 



V. Final Conclusions. 



The foregoing experiments prove conclusively that Flacherie 

 has an injurious influence upon the prosperity of the gypsy 

 moth caterpillars, this influence varying according to the man- 

 ner and time of the appearance of the disease. There was 

 no difference noticed in the progress of the wilt which broke 

 out naturally and that of the artificially developed Flacherie. 

 The latter, however, is probably the more important factor, 

 for with its help we may be able to introduce the disease among 

 caterpillars of localities in which the wilt, perhaps, would not 

 make its appearance naturally. The infection of a place with 

 sick material only seems to be, as regards the " dying off " of 

 the caterpillars, less favorable for the spread of Flacherie than 

 with material which already contains a number of dead indi- 

 viduals. In selecting the localities in which the disease is to 

 be introduced, it is unimportant whether the caterpillars of the 

 gypsy moth are present in large or small numbers. It is true 

 the wilt will get a stronger foothold and attain a greater viru- 

 lence the larger the number of caterpillars. In places, how- 

 ever, which are not badly infested, the disease will also spread 

 to the healthy caterpillars, as was shown by several of the 

 experiments. According to the observations, we are almost 

 inclined to believe that the direction of the wind plays an 

 important role in spreading the disease. This opinion is 

 strengthened especially by the observations made in Concord 

 and West Bedford. 



Wherever the naturally as well as the artificially developed 

 Flacherie occurs the female caterpillars will always succumb 

 to it more readily than the male. This may perhaps be due to 

 the fact that they require a longer time to mature than the 

 male caterpillars. If, at the flying period of the moth, we visit 

 such a diseased locality, one in which during the summer 

 the caterpillars were quite plentiful, we find ourselves sur- 

 rounded by male moths, which to the superficial observer 

 would indicate that the wilt had caused no considerable diminu- 

 tion. As soon, however, as we begin to search for adult females, 

 we discover that they are present in a decided minority, and 



