200 



TENTH ANNUAL REPORT. 



a 



Fig. 7.— The Forest Tent Caterpillar : a, mark- 

 ings on one ring of the back; 6, markings on one 

 ring of the side. 



ingl}^ destructive outbreak of the forest tent caterpillar 

 (Clisiocampa disstria), which extended over a large part of 



the state. This was 

 a continuance of the 

 irruption of this in- 

 sect noted in the in- 

 sect record for 1897,* 

 although as was to be 

 expected the outbreak 

 this year was more 

 serious and extended 

 over a wider area. 

 The caterpillars were 

 most abundant in the 

 western part of the 

 state, especially in the Connecticut valley, w^here extensive 

 forest areas were defoliated by them. For, unlike the common 

 AMERICAN TENT CATERPILLAR {CUsiocampa americano), this 

 forest species does not as a rule confine its attack to three or 

 four sorts of trees, but feeds upon the foliage of nearly all 

 deciduous species. The nearly full grown caterpillar is rep- 

 resented in Fig. 7. As will be seen by comparing this picture 

 with Fig. 8, which represents the American Tent Caterpillar, 

 the two species are similar; but they may easily be distin- 

 guished by the differences in the markings of the line along 

 the middle of the back. In the forest caterpillars this line is 

 interrupted, consisting of a series of markings like that shown 

 in the middle of Fig. 7 a, while in the common tent caterpillar 

 the line along the middle of the back is continuous. 



These caterpillars have attacked nearly all kinds of decid- 

 uous trees, causing special damage to shade trees like the elm 

 and maple. Many sugar orchards appear to have sustained 

 injury that will lessen their productiveness in the immediate 

 future. As a rule, the attack appears to have been more 



*Bunetin48, p,142. 



