BULLETIN 76: THE FOREST CATERPILLAR 



{CUsdocampa dissiria Hub.) 

 By G. H. Perkins 



I. INTRODUCTION 



This insect is closely allied to the apple tree tent-caterpillar, and has 

 often been confused with it by those not familiar with different species of 

 insects. This is not strange because both in the larval and mature states the 

 two species are much alike. The name forest tent-caterpillar is 

 that by which this species has been long and widely known, but it is ob- 

 jected to by some of our best entomologists on the ground that it is not 

 appropriate since the caterpillar does not make a tent, but only a sort of 

 mat which lies close to a large limb or to the trunk of an infested tree. 

 While this name is, as has been stated, that which is most common, 

 there are several others which have been more or less used at one time or 

 another. Without entering into a discussion of the merits of any of these 

 names, but simply for convenience the insect will be termed throughout 

 this bulletin the forest caterpillar, for the reason that, as this bulletin is 

 prepared not for the country at large but for the people of Vermont, it 

 seems to the writer best to use the name by which the insect is most com- 

 monly known in this state. 



The ravages of the forest caterpillar began to attract attention to some 

 extent in this state in 1895. In 1896 they had become so extensive and 

 wide spread that no little alarm was created lest the maple groves and 

 shade trees of the state should be seriously injured. The continued abund- 

 ance of the caterpillars and the very great damage which they have com- 

 mitted during 1898 and 1899 have shown that these fears were only too 

 well grounded. In some places in the state the damage which was done in 

 1896 was as great as in any subsequent year, but as a whole the state has 

 suffered more during the past two years than previously. Although I do 

 not find any record of an attack so wide spread and destructive as has been 

 that of the last three years, yet the forest caterpillar is not a new insect in 

 Vermont. In a book published in 1791 I find an account of the presence in 

 great numbers of a caterpillar which seems to be the same as our present 

 pest. At different times since the beginning of the century there have been 

 seasons in which this insect has committed more or less noticeable damage 

 in Vermont, and, indeed, in nearly every state in the Union and in parts of 

 Canada. Still, the recent ravages far exceed any that have taken place 



