10 
INTRODUCTION. 
flowering plants in Massachusetts, ancl it will he within 
bounds to estimate the species of insects at 4,800, or in the 
proportion of four to one plant. I o 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. Coleoftera ( Beetles ). Insects with jaws, two thick 
wing-covers meeting in a straight line on the top of the back, 
and two filmy wings, 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 
less distinct and unconfined. 
Many of these insects, particularly in the larva state, are very 
injurious to vegetation. The tiger-beetles ( Cicindeladee *), the 
predaceous ground-beetles ( Carabidce ), the diving-beetles ( Dylis - 
cidee), the lady-birds ( Coccinelladce ), and some others, are emi- 
nently serviceable by preying upon caterpillars, 
plant-lice, and other noxious or destructive insects. 
The water-lovers ( Hydrophilida ;), rove-beetles ( Sta- 
phylinidce), carrion-beetles ( Silphadce ), skin-beetles 
( Dermestadce , Byrrhidce, and Trogidee), bone-beetles 
(some of the Nitiduladce and Cleridee), and vari- 
ous kinds of dung-beetles ( Spharidiadce , Ilisteridee , 
Geotrupidcc, f Copridida ,t and Aphodiadce f), and 
clocks ( Pimeliades and Bl apt idee), act the useful 
part of scavengers, by removing carrion, dung, and 
other filth, upon which alone they and their larva; 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. 18.35. 
t All the Scaraboeidas of my Catalogue, from Ateuchus to Geotrupet inclusive, 
to which may be added many included in the genus Scarabaus. 
Fig. 1. 
•mt 
Tenebrio molitor. 
(Meul-worm.) 
Larva. 
