10 INTRODUCTION. 



flowering plants in Massachusetts, and it will be within 

 bounds to estimate the species of insects at 4,800, or hi the 

 proportion of four to one plant. To facilitate the study of 

 such an immense number, some kind of classification is neces- 

 sary ; it will be useful to adopt one, even in describing the 

 few species now before us. The basis of this classification is 

 founded upon the structure of the mouth, in the adult state, 

 the number and nature of the wings, and the transformations. 

 The first great divisions are called orders, of which the fol- 

 lowing seven are very generally adopted by naturalists. 



1. Coleoptera (Beetles). Insects with jaws, two thick 

 wing-covers meeting in a straight line on the top of the back, 

 and two filmy w T ings, which are folded transversely. Trans- 

 formation complete. Larvae, called grubs, generally provided 

 with six true legs, and sometimes also with a terminal prop- 

 leg ; more rarely without legs. Pupa with the wings and the 

 legs distinct and unconfined. 



Many of these insects, particularly in the larva state, are very 

 injurious to vegetation. The tiger-beetles (Cicindelad<z*), the 

 predaceous ground-beetles (Carabidce), the diving-beetles (Dytis- 

 cidcs), the lady-birds (Coccinelladce), and some others, are emi- 

 rig> j nently serviceable by preying upon caterpillars, 



plant-lice, and other noxious or destructive insects. 

 The water-lovers {Hydrophilidce), rove-beetles (Sta- 

 phylinidce), carrion-beetles (Silphadce), skin-beetles 

 (Dermestadce, Byrrhidce, and Trogidce), bone-beetles 

 (some of the Nitiduladce and Cleridce), and vari- 

 ous kinds of dung-beetles (Sphceridiadce, Ifisteridce, 

 )iitor. GeotrupidcB,^ Coprididoe^ and Aphodiada |) , and 

 (Meal-worm.) clocks {Pimeliadce and JBlaptidce), act the useful 

 part of scavengers, by removing carrion, dung, and 

 other filth, upon which alone they and their larvae subsist. Many 



* See the Catalogue of Insects appended to Professor Hitchcock's Report on 

 the Geology, Mineralogy, Botany, and Zoology of Massachusetts. 2d edit. 8vo. 

 Amherst. 1835. 



t All the Searabasidse of my Catalogue, from Ateuchus to Geotrupes inclusive, 

 to which may be added many included in the genus Scarabceus. 



