CHAPTER II. 



SKETCH OF THE ANATOMY AND PHYSIOLOGY OF INSECTS. 



The parts of the insect which are employed in description are the antennfp, the segments, 

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

 necessary to describe somewhat at length. The three divisions of the body are marked by 

 deep iqcisions, by which the head, thorax and abdomen, or hindr-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 or 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 parietes 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 also denominated wing-covers or cases, and are often finely sculptured, punctured or 

 ornamented : to these the insect frequently owes its beauty ; upon these, too, the fine 

 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 composed of a fine network traversed 

 longitudinally and obliquely 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 appears perfect when 

 first captured ; showing thereby their power and ability to perform the natural functions 

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



