INTRODUCTION. 7 



The eyes of adult insi'c-ts, tlioiigii apparciilly two in iintiil)('r, 

 are compound, each consisting of a great number of single eyes 

 closely vmited together, and incapable of being rolled in their 

 sockets. Such also are the eyes of the larvte, and of the active 

 pupa3 of those insects that imdergo an iiii[)(M-reet transformation. 

 Moreover, many winged insects have one, two, or three little 

 single eyes, placed near each other on the crown of the head, 

 and called ocelli^ or eyelets. The eyes of grubs, caterpillars, 

 and of other completely transforming larvae, are not compound, 

 but consist of five or six eyelets clustered together, without 

 touching, on each side of the head; some, however, such as 

 maggots, are totally blind. Near to the eyes are two jointed 

 members, named antennrc, corresponding, for the most part, in 

 situation, with the ears of other animals, and supposed to be 

 connected with the sense of hearing, of touch, or of both united. 

 The antennsB are very short in larvae, and of various sizes and 

 forms in other insects. 



The mouth of some insects is made for biting or chewing, 

 that of others for taking food only by suction. The biting- 

 insects have the parts of the mouth variously modified to suit 

 the nature of the food ; and these parts are, an upper and an 

 under lip, two nippers or jaws on each side, moving sidewise, 

 and not up and down, and fovir or six little jointed members, 

 caRed palpi or feelers, whereof two belong to the lower lip, and 

 one or two to each of the lower jaws. The mouth of sucking- 

 insects consists essentially of these same parts, but so difierent 

 in their shape and in the purposes for which they are designed, 

 that the resemblance between them and those of biting-insects 

 is not easily recognized. Thus the jaw^s of caterpillars are 

 transformed to a spiral sucking-tube in butterflies and moths, 

 and those of maggots to a hard proboscis, fitted for piercing, as 

 in the mosquito and horse-fly, or to one of softer consistence, 

 and ending with fleshy lips for lapping, as in common flies ; 

 while in bugs, plant-lice, and some other insects resembling 

 them, the parts of the mouth undergo no essential change from 

 infancy to the adult state, but are formed into a long, hard, 

 and jointed beak, bent under the breast when not in use, and 

 designed only for making punctures and drawing in liquid 

 nourishment. 



