NEW YORK STATE MUSEUM 



The Braconidae include some very important parasites, specially of 

 wood-boring larvae and of a number of leaf feeders. This group may be 

 best recognized by such species asBracon simplex Cress., a form which 

 is well known to live on a number of borers, and also by the tiny Micro- 

 gasters, minute species which frequently occur in immense numbers in our 

 larger leaf feeders, and when maturity is attained, make their way out 

 through the body wall of their hosts and spin tiny, nearly cylindric, snow 

 white cocoons on the body of the victim, as represented at plate 44, figure 2. 



The Evaniidae or ensign flies, as they are termed by Professor Com- 

 stock, constitute a parasitic group which may be easily recognized by the 

 peculiar manner in which the abdomen is carried. The latter is quite 

 slender, attached to the dorsum of the metathorax, and is carried in an 

 elevated position resembling a flag or ensign. 



The Chalcididae comprise an immense number of very small parasites, 

 some of which are exceedingly valuable agents in controlling our native 

 insects. A number of species are noticed in connection with their hosts and 

 the general characteristics of the group may be learned by reference to 

 subsequent pages. 



The Proctotrypidae in spite of the long family name, are smaller insects 

 than the preceding and a number of them are well known as important egg 

 parasites of some of our more injurious species. 



Practically all of the dipterous parasites belong to the Tachinidae, a 

 large family whiich comprises forms having much the appearance of the 

 common house fly. These insects are more general in their food habits 

 than most of the hymenopterous parasites and frequently attack insects 

 belonging to very different groups. Occasionally members of this family 

 are exceedingly abundant and have a very important part in reducing the 

 numbers of some insect pest. This is particularly true of the notorious 

 army worm, H e 1 i o j) h i 1 a unipuncta Haw. It has been recorded in 

 connection with this latter insect that its parasites are sometimes so abundant 

 as to appear in swarms about their victims and it is by no means uncommon 

 to meet with an army worm bearing from 6 to 7 or even more pearly white 



