INJURIOUS INSECTS. 119 



in Maine in regard to the sudden appearance and disappearance 

 of insects. A few j-ears ago a species of moth in prodigious 

 numbers was destroying the evergreen forests in three or four of 

 the western counties, so that the owners cut down their trees by 

 the acre to save their lumber. It was of the same famil}' as the 

 codling moth and had been so rare that onh* three specimens were 

 known in all the collections of the world. Professor Fernald pub- 

 lished an account of its history in the " American Naturalist" and 

 collected specimens from which all sorts of parasites emerged. 

 The next year there were no more ; the parasites had destroyed 

 them. This great abundance gave the parasites a chance to mul- 

 tiply and it will be several years before the cj'cle comes round 

 again. 



On his father's farm, at Mount Desert, the cabbage worm was 

 so abundant as almost to force him to give up the cultivation of 

 cabbages. But Professor Fernald found some pupaj under clap- 

 boards from one of which he bred forty-two parasites. These he 

 sent to his father, and in a few years there were no cabbage 

 butterflies on his farm. 



There are two species called tent caterpillars, of which that 

 known as the forest caterpillar has a wider range of food plants 

 than the other, and at times there have been very great outbreaks 

 of it. At one time an army of them crossed the track of the 

 European and North American railway in such numbers as to stop 

 the trains, so many being killed on the track as to make the rails 

 so slippery that the wheels would not take hold. They climbed 

 over Professor Fernald's house and into it, so that he was quite 

 disgusted. The next year he found but few and these were stiff 

 with a vegetable parasite which had destroj'ed them. His view 

 is that such a multiplicity tends also to create a multiplicity of 

 parasites which are destructive to them, so that their very abun- 

 dance is also their destruction. 



William D. Philbrick asked how to destro}' the squash borer 

 and cabbage maggot. 



Professor Fernald replied that these two insects probably repre- 

 sent five or six different species, but he was unable to give any 

 practical, easy method for their destruction. Bisulphide of carbon 

 has been used in the West, and was said to be very efficacious ; a 

 teaspoonful was placed in a hole made near the roots of the plant 

 and the earth was pressed down over it, but he had no practical 

 experience on this point. 



