INDIRECT BENEFITS DERIVED FROM INSECTS. 261 



within proper limits, are other insects; and to these I 

 shall now call your attention. 



Numerous are the tribes upon which this important 

 task devolves, and incalculable are the benefits which 

 they are the means of bestowing- upon us ; for to them 

 we are indebted, or rathei' to Providence who created 

 them for this purpose, that our crops and grain, pur 

 cattle, our fruit- and forest-trees, our pulse and flowers, 

 and even the verdant covering of the earth, are not 

 totally destroyed. Of these insects, so friendly to man, 

 some exercise their destructive agency solely while in 

 the larva state ; others in the perfect state only ; others 

 in both these states; and lastly, others again in all the 

 three states of larva, pupa, and imago. For order's 

 sake, and to give you a more distinct view of the sub- 

 ject, I shall say something on each separately. 



The first, those which are insectivorous only in their 

 larva state, may be further subdivided into parasites and 

 imparasites, meaning by the former term those that feed 

 upon a living insect, and only destroy it when they have 

 attained their full growth ; and by the latter, those that 

 prey upon insects already dead, or that kill them in the 

 act of devouring them. 



The imparasitic insect devourers chiefly belong to the 

 Hymenoptera order ; and though is it in the larva state 

 that their prowess is exhibited, the task of providing 

 the prey is usually left to the female, of which each spe- 

 cies for the most part selects a particular kind of insect. 

 Thus many species of Cerceris and the splendid Chry- 

 sidcE feed upon insects of their own order. One of the 

 latter (Panorpes incarnata, Latr.) commits her eggs to 

 the progeny of Bemhex rostrata: another (Chrysis bi' 

 dentata) atta.cks the young of Vespa spinipes. . ^ 



