8 INSECTS INJURIOUS TO VEGETATION. 



upon their last or adult state, wherein they no longer increase in 

 size, and during which they provide for a continuation of their 

 kind. This period usually lasts only a short time, for most in- 

 sects die immediately after their eggs are laid. Bees, wasps, 

 and ants, however, which live in society, and labor together for 

 the common good of their communities, continue much longer in 

 the adult state. 



In winged or adult insects, two of the transverse incisions, with 

 which they are marked, are deeper than the rest, so that the body 

 seems to consist of three principal portions, the first whereof is 

 the head, the second or middle portion the thorax, or chest, and 

 the third or hindmost the abdomen, or hind-body. In some 

 wingless insects these three portions are also to be seen ; but in 

 most young insects, or larvae, 'the body consists of the head, and 

 a series of twelve rings or segments, the thorax not being dis- 

 tinctly separated from the hinder part of the body, as may be 

 perceived in caterpillars, grubs, and maggots. 



The eyes of adult insects, though apparently two in number, 

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

 closely united together, and incapable of being rolled in their 

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

 pupae of those insects that undergo an imperfect 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 con- 

 sist of five or six eyelets clustered together, without touching, on 

 each side of the head ; some, however, such as maggots, are total- 

 ly blind. Near to the eyes are two jointed members, named an- 

 tennce, 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 antennae are very 

 short in larvae, and of various sizes and forms in othef insects. 



The mouth of some insects is made for biting, that of others 

 for taking food only by suction. In biting-insects the parts of the 

 mouth, which are variously modified to suit the nature of the food, 

 are these : an upper and an under lip, two nippers or jaws on 

 each side, moving sidewise, and not up and down, and four or six 

 little jointed members, called palpi or feelers, whereof two belong 



