rHAl'TKK II. 



SKETCH OF THE ANATOMY AND PHYSIOLOGY OF INSECTS. 



The piirts of the insect which are eiuployed in description are the antennae, the segments, 

 the wings and nervures, the eyes, the parts forming the mouth, etc. ; and these it will be 

 necessiu-y to describe somewhat at length. The three divisions of the body are marked by 

 deep incisions, by which the head, thorax and abdomen, or hind-body as it is sometimes 

 called, are always distinct in the perfect insect ; but in the larva there are only two divi- 

 sions, the head and body. The middle, or thorax, supports the head and wings. The head is 

 armed with jaws >>v mandibles and palpi, and ornamented or surmounted by the antennae, 

 which, in some insects, are much larger than their bodies, and are made up of many joints 

 gradually tapering to a point. 



The wings of beetles are composed of dissimilar pieces, lying, when at rest, one above 

 the other. The upper or outer wing is thick, and shaped to the parictes of the abdomen, 

 being convex above and concave below : it protects the true wing, which is delicate and 

 studiously folded, and is only elevated in flight, in order to give play to the true wings. 

 The upper wings are called elytra, to distinguish them from the reticulated wing ; they 

 are als> denominated ifi/jg-forers or crt^fs, and are often finely sculptured, punctured or 

 ornamented : to these the insect frequently owes its beauty ; upon these, t<.io, the ^ne 

 colors are impressed, which are often of a splendent hue or lustre. In other orders of in- 

 sects the four wings are entirely reticulated, or c<imp<'Sed of a fine network traversed 

 longitudinally and oblicpiely by nervures which branch in the same species in a certain 

 manner, which, from their constancy, have been employed by systematists to aid in clas- 

 sifying, and as characteristics of genera. The wings are still farther modified in the Le- 

 pidoptera ; the network is more compact and close, and is covered with fine scales but 

 slightly attached, which appear to the unassisted eye like meal of a pearly hue. Butterflies 

 and moths are provided with this peculiar wing, which, though extremely delicate and 

 always injured when slightly touched with the finger, yet always api)ears perfect when 

 first c^iptured ; showing th<>roby tlieir power and ability to perform the natural functions 

 for which they were designed, without sustaining the loss of this delicate substance. 



