INTRODUCTION. 15 



removal of these dead and useless substances, and make room for new 

 and more vigorous vegetation. Some of these wood-eating insects, with 

 others, when transformed to flies {Asilidic, Rhagionida., Dolichopid(P, 

 and Xylophagida), prey on other insects. Some (Si/rphidcc), though 

 not predaceous themselves in the winged state, deposit their eggs among 

 plant-lice, upon the blood of which their young afterwards subsist. 

 Many (Conopidce, excluding Stomoxys, Tachimc, Ocijpfera;, Phorce, &lc.) 

 lay their eggs on caterpillars, and on various other larvse, within the 

 bodies of which the maggots hatched from these eggs live till tliey 

 destroy their victims. And finally others {Anthracidce and Volucellce) 

 drop their eggs in the nests of insects, whose offspring are starved to 

 death, by being robbed of their food by the offspring of these cuckoo- 

 flies. Besides performing their various appointed tasks in the economy 

 of nature, flies, and other insects, subserve another highly important 

 purpose, for which an all-wise Providence has designed them, namely, 

 that of furnishing food to numerous other animals. Not to mention the 

 various kinds of insect-eating quadrupeds, such as bats, moles, and the 

 like, many birds live partly or entirely on insects. The finest song- 

 birds, nightingales and thrushes, feast with the highest relish on magsots 

 of all kinds, as well as on flies and other insects, while the warblers, 

 vireous, and especially the fly-catchers and swallows, devour these two- 

 winged insects in great numbers. 



The seven foregoing orders constitute very natural groups, 

 relatively of nearly equal importance, and sufficiently distinct 

 from each other, but connected at different points by various 

 resemblances. It is impossible to sllo^v the mutual relations 

 of these orders, when they are arranged in a continuous series, 

 but these can be better expressed and understood by grouping 

 the orders together in a cluster, so that each order shall come 

 in contact with several others. 



Besides these seven orders, there are several smaller groups, 

 which some naturalists have thought proper to raise to the rank 

 of independent orders. Upon the principal of these, a few 

 remarks will now be made. 



The little order Strepsiptera of Kirby, or Rhipiptera of 

 Latreille, consists of certain minute insects, which undergo 

 their transformations within the bodies of bees and wasps. 

 One of them, the Xenos Peckii, was discovered by Professor 

 Peck in the common brown wasp [Polistes fuscata) of this 



