APPENDIX. 



xli 



Previous to my visit to Maiden I felt some doubt as to whether 

 it was possible to exterminate the gypsy moth, as I had had 

 some previous knowledge of it and of its ravages in Massa- 

 chusetts, being at Amherst when it was first reported to the ex- 

 periment station there in 1889, and having carefully looked over 

 the matter at that time. Since my visit a careful considera- 

 tion of the methods used and of the results already obtained 

 has convinced me that extermination is not only probable, but 

 certain, if the work be prosecuted for a sufficient length of 

 time. 



On one or two points I have gathered impressions which may 

 perhaps be worthy of mention here : — 



1 . I think that the position so far held by the committee with 

 reference to the effect of parasites is a wise one. I have never 

 heard of a case where an insect was exterminated by its parasites, 

 the relation of the two forms at any one time being, in numbers, 

 very close. A reduction in the numbers of the host is always 

 followed by a similar reduction in the numbers of the parasites, 

 leaving to those individuals of the host which have escaped an 

 opportunity for rapid and unchecked increase until overtaken by 

 a corresponding but later increase in numbers of the parasites. 

 For this reason parasites cannot be relied upon to do the work 

 needed in the case of the gypsy moth. 



2. The method of burning over infested areas in connection 

 with burlapping the trees seems to me to be a most effective 

 method of procedure if the precaution of burning for a sufficiently 

 great distance beyond the limits of the infested area be carefully 

 observed. My impression is that the edge of the burned area 

 should always be at least two hundred feet outside these limits, 

 as far as these can be ascertained. 



The work so far accomplished shows on its face that the 

 methods in use are the result of experience, and that they are 

 most efficacious. 



It seems to me that two things are greatly to be feared : — 



1. That the time is near when searches with negative results 

 may tend to produce carelessness on the part of the searchers. 



2. That the apparent disappearance of the moths may lead 

 the Legislature into the error of abolishing the committee at the 

 time when its work will show the fewest results, but will in reality 

 be the most valuable, — in fact, would be absolutely necessary to 

 insure the prevention of some future invasion. 



The work done by the committee in the way of testing insecti- 

 cides in the field at Maiden and in the laboratory at Amherst is 

 of great value, and the importance of learning with the greatest 



