ORGANS OF INSECTS DESCRIBED. 7 



spots ; and grubs, after their first transformation, are often 

 named nymphs, for what reason does not appear. At the 

 end of the second period, insects again shed their skins, and 

 come forth fully grown, and (with few exceptions) provided 

 with wings. Thus they enter 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 insects die imme- 

 diately after their eggs are laid. Bees, wasps, and ants, 

 •however, which hve 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 larvse, the body 

 consists of the head and a series of twelve rings or segments, 

 the thorax not being distinctly separated fi-om the hinder part 

 of the body, as may be perceived in caterpillars, grubs, and 

 maggots. 



The eyes of adult insects, though apparently two in num- 

 ber, 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 larvte, 

 and of the active pupse 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 cro^vn of the head, and called ocelli, or eyelets. 

 The eyes of grubs, caterpillars, and of other completely trans- 

 forming larvse, 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 bhnd. 

 Near to the eyes are two jointed members, named aidennce, 



