10 INTRODUCTION. 



flowering plants in Massachusetts, and it will Ije within 

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

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

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

 sary ; it will be useful to adopt one, exen 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 Ijy naturalists. 



1. CoLEOPTERA (^BeetUs). Insects with jaws, two thick 

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

 and two filmy wings, Avhich are folded transversely. Trans- 

 formation complete. Larvae, called grubs, generally provided 

 w^ith six true legs, and sometimes also wnth a terminal prop- 

 leg ; more rarely without legs, Pvipa 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 {^Cicindeladce*)^ the 

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

 cidce), the lady-birds ( Cocci neliad/x), and some others, are emi- 

 Pi I 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 Nitididadce and Cleridce), and vari- 

 ous kinds of dung-beetles {SphxEridladiE, Histeridce, 

 Tenebrio moiitor GeotnipidcB,'\ Coprididce,'\ and Aphodiadce'f), and 

 (Meal worui.) clocks (PhneliadcB and Blaptidce), act the useful 

 ^"'"' part of scavengers, by removing carrion, dung, and 



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



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

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

 Amherst. 1835. 



t All the ScarabfeidfE of my Catalogue, from Ateiichus to Geotrvpes inclusive, 

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



