310 BOARD OF AGRICULTURE. [Pub. Doc. 



hatched and on the move. This obstacle must always be over- 

 come by destroying the eggs, so that no caterpillars may emerge. 

 Experience has shown that this is the most practical method of 

 dealing with the moth. The chief objection urged to this method 

 is, that some of the eggs are now laid where it is impossible to 

 get to them. A few clusters of eggs here and there will at first 

 escape the general destruction. When few remain, however, 

 nature will aid materially in extermination. It has been stated 

 that the creatures have spread over a comparatively small area in 

 twenty-one years or more. They migrate slowly by a gradual 

 increasing and spreading of the main body, and are thus vn\ 

 destructive. Recent investigations in the territory outside of the 

 thickly infested district have furnished us with a series of data 

 from which we glean the following : — 



1. We find that many egg-clusters are infertile. 



2. Some that are fertile have not hatched. 



3. Others, that have evidently hatched and gone through their 

 transformations, have apparently never reproduced. 



4. In other cases the entire colony has been destroyed in some 

 manner during its first or second season. 



In many cases where the eggs have proved fertile the rate of 

 increase in number's has been very small during the second and 

 third years. In fact, the instance where an isolated colony greatly 

 increases in the first few years appears to be the exception. 



Eggs are infertile where the female which has deposited them 

 has been carried beyond the reach of males of the same species. 

 Predatory larvae attack the eggs of these and other insects, and, 

 where only one or two eggs-clusters are found by these larva 1 , they 

 are generally utterly destroyed. Minute insects of various kinds 

 also destroy them. As soon as the caterpillars are hatched they 

 are exposed to the vicissitudes of our New England climate aud to 

 the attacks of birds and parasitic insects. In the smaller suburban 

 towns, where the English sparrow is not abundant, our native 

 birds destroy vast numbers of injurious insects. During the 

 past season, thirteen species of birds have been observed to feed 

 on the gypsy moth in all its stages. 



Experience has demonstrated that where a species is reduced in 

 numbers to a few individuals, and those individuals isolated, the 

 chances are in favor of their extermination by natural causes. It 

 is <>ur hope aud purpose to so reduce the numbers of the gypsy 

 moth that extermination may eventually be accomplished. 

 Respectfully submitted, 



E. II. FORBUSII, 



Director of Field Work. 



