14 



among them, and conditions were therefore most suitable for the 

 spread of the wilt. Always in the places that have been in j ured 

 by gypsy moth caterpillars in previous years, there is a pre- 

 disposition on the part of caterpillars of the following year 

 toward Flacherie. The heavy defoliation checks the normal 

 metabolism of the attacked vegetation, which causes a weak 

 and sickly development of the shoots, and these therefore do 

 not furnish the caterpillars sufficiently wholesome nourishment. 

 It should be remembered that these facts, in the long run, 

 mean a self-protection of the vegetation. If at this time dead 

 and sick material is introduced among the caterpillars in such 

 a locality, the organisms of the disease will act readily upon 

 the individuals present. Infection will take place even in 

 cases where a locality is badly infested by the caterpillars for 

 the first time, because one can always find a large number of 

 weak and therefore susceptible specimens. Then, as the disease 

 progresses, it acquires such virulence that even the previously 

 healthy specimens become infected. 



In the article mentioned I called attention to other ways in 

 which the caterpillars advance the infection among themselves, 

 that is, during the resting period, during the feeding time, 

 etc., and how easily the disease may be carried over by the 

 caterpillar to its pupal stage. The great probability of an 

 economic value in Flacherie for destroying the gypsy moth was 

 suggested, but it was thought that the experiments of only a 

 single year had better not be taken as a comprehensive method 

 for the practical use of the wilt, and that further experiments 

 should be undertaken on a larger scale to substantiate the 

 obtained results. 



III. Flacherie Experiments in 1910. 



A. GENERAL. 



In the spring of 1910 the author was requested, by the State 

 Forester of Massachusetts, to make similar experiments on a 

 large scale in different parts of the State. 1 These experiments 

 were undertaken with the help and kind encouragement of 

 Prof. W. M. Wheeler. I would also express my indebtedness 



1 Cf.: "Sixth Annual Report of the State Forester of Massachusetts," 1909, p. 86. 



