BENEFICIAL INSECTS, PREDACEOUS AND PAKASITIC. 41 



changes to a pupa, apparently iinaffected. But now the 

 maggots have reached their full size, and each spms up a 

 small silken cocoon inside the 2:»upa, entirely filling up its 

 now dead shell, and instead of a beautiful moth apj^earing 

 in the spring, from a round hole in the side of the pupa, 

 or cocoon, a horde of small flies are seen to emerge. 



Thus large numbers of such pests as the Apple-tree 

 Tent-caterpillar {CUsiocam2)a americaiia), Bag-worms 



Fig. 22. — Maggots of Pimj)la iriqiiisUor, a parasitic Ich 

 fly, feeding on a caterpillar which had spun its cocoon 

 ready to pupate. (Original.) 



ncumon- 

 spun its cocoon and was 



{Tliyridopteryx ep1iemer(efor})iis), cater^jillars of the swal- 

 low-tailed butterflies which feed upon parsley, carrots, 

 etc., and a host of others, are consumed by members of 

 this family. 



Those belonging to the genus Opliion are partial to the 

 large American silkworms which produce some of our 

 largest and most beautiful moths, and difficulty is fre- 

 quently experienced in rearing a desired number of moths 

 on account of the large ^^er cent of cocoons parasitized. 



The species of the family Braconidce are very similar to 

 those of the preceding one, and contain some eqiiany 



