526 COLLEGE OP AGHICULTURB 



It is hardly probable that the attack this year will prove fatal 

 to many of the trees, but if renewed! another season many of 

 the trees will, beyond a doubt, be seriously injured or killed. 

 Numbers of the maple groves that were defoliated early in the 

 season sent out a second growth of leaves, but these would assist 

 very little in the nutrition of the trees. 



New Hampshire is by no means the only state that has suf- 

 fered from the attacks of S. guttivitta this year, Maine, Ver- 

 mont and New York having all had serious outbreaks. 



So far we can only conjecture as to the cause of the appar- 

 ently sudden outbreak. It seems probable that these worms 

 have been multiplying for some time, but have been so well pro- 

 tected in the dense forests that their presence has not been 

 detected. On the other hand, there seems little doubt that the 

 species has been held in check by parasites, or other natural 

 enemies, which for some reason were unusually scarce this sea- 

 son, allowing the caterpillars to multiply abnormally. During 

 the entire summer, in which large numbers of larvae were reared 

 in the laboratory, but one species of parasite was found (an 

 Ichneumon) and that occurred in only two larvae. Usually half 

 the larvae of our moths and butterflies which reach any size in 

 the open, will be found to contain parasites. According to Miss 

 Edith Patch of the Maine Agricultural Experiment Station, 

 Ichneumon suilatus was quite numerous this season in Maine. 

 This is probably a natural parasite of Heterocampa, which for 

 some unknown reason became very scarce, allowing the host to 

 multiply to such an appalling extent. Of the predaceous insects 

 but two were at all numerous. The Fiery Ground Beetle, 

 {Calasoma calidum), was quite plentiful in different parts of 

 the state. This large bright-colored beetle doubtless destroyed 

 great numbers of the caterpillars, but in the worst infested 

 regions the beneficial results were not very apparent. The other 

 predaceous insect, one of the soldier bugs, Podissus placidus, far 

 outnumbered the ground beetles, and might be seen busily suck- 

 ing the juices from the larvae in almost any infested area. 



Another factor in the outbreak was the noticeable scarcity 

 of birds of all kinds. Not that this was the prime cause for 

 such large numbers of caterpillars, but their numbers would evi- 

 dently have been greatly reduced had there been more birds in 

 the woodland. In many sections of the infested region one would 

 travel all day, and not find half a dozen birds of any descrip- 

 tion. As before stated, Mr. W. M. Barrows in driving from 

 Grafton to Bristol, a distance of fourteen miles, reports having 



