PARASITES OF THE GYPSY AND BROWN- 

 TAIL MOTHS. 



NATURE OF INSECT PARASITISM. 



It is probable that the total number of different species of 

 insects which are native to Massachusetts is not far short of 10,- 

 000, if indeed it does not exceed this number. A large propor- 

 tion of these are plant feeders, some of them sucking the sap, 

 others eating the foliage, and others still boring in the roots, 

 seeds or stems. A great many feed upon dead vegetable matter, 

 or upon the lower plants, such as mushrooms and other fungi. 



Several thousand, possibly half of the total, feed upon animals 

 or upon dead animal matter, and by far the larger part of these 

 prey upon other insects, — principally, but by no means exclu- 

 sively, upon those which are plant feeders. It is largely through 

 this continuous warfare that the plant-feeding insects are held in 

 check, and prevented from increasing to such numbers as to be- 

 come a menace to vegetable life in general. 



The insects which subsist upon other insects may roughly 

 be divided into two classes, according to the methods of their 

 attack. The predatory, like the other predatory animals, wander 

 about, attacking and devouring the weaker species or individ- 

 uals. For the most part they are very catholic in their tastes, 

 and will attack almost any other insect which they may chance 

 to encounter in their favored haunts. The parasitic, on the con- 

 trary, are in most instances very closely restricted in the choice 

 of their prey, and have a very different method of attack. 



Instead of falling upon and devouring a weaker insect, they 

 frequently attack and destroy those which are much larger and 

 stronger in every way than themselves. This is accomplished by 

 the deposition of an egg, or in some instances a living maggot, 

 within or upon the body of the selected victim, or upon its food, 

 or in some other situation. The young larva, hatching from the 



