152 APPLIED ENTOMOLOGY 



The eggs of the stylops appear to hatch within the body of the mother 

 and the young escape by passing from the body out into the space between 

 this and the pupa case of the parent in which it remains, and then through 

 an opening in this at the cephalothorax, thus reaching the open air. 

 They are now on the body of the parental host and this insect may carry 

 them to its nest, where if it is a colonial form, the stylops may find young 

 to attack there. It is generally probable though, that they leave the 

 parental host at some place (possibly a blossom) where other insects of 

 the host species will be liable to visit. Transferring onto such individuals 

 as chance may permit, the stylopids finally arrive where larvae of the 

 proper species are available, and at once attack them. Thus far they 

 have been active little six-legged larvae, but after burrowing into the 

 body of their host larvae they change greatly, becoming worm-like and 

 legless. The males finally enter a pupa stage, after which the adults 

 escape, but the females remain throughout the rest of their life in the 

 bodies of their hosts. 



Where stylopids are abundant and attack injurious species of insects, 

 such as are most at least of the Homoptera, the stylopized individuals, 

 being unable to reproduce, become of lessened importance and their 

 parasites must be considered as beneficial. Most of the Hymenoptera 

 they attack, however, are beneficial and parasitism in such cases can 

 hardly be considered helpful to man. The group is not sufficiently 

 abundant though, to be an important factor under ordinary conditions, 

 as only about a hundred species are known, but these are widely dis- 

 tributed over the globe. 



