INSECTS INJURIOUS TO VEGETATION. 



441 



as the name implies, are gilt or adorned with 

 'golden spots ; and grubs, alter their first tr;uis- 

 formation, are often named nymphs, for what 

 reason does not appear. At the end of the sec- 

 ond period insects again shed their skins, and 

 come fortli fully grown, and (\vith few excep- 

 tions) provided with wings. They thus enter 

 upon tlieir Ia>;t or ailult state, wlierein tliey no 

 longer increase in size, aiid during which 

 they provide for a continuation of their kind. 

 This period usually lasts only a short time, for 

 most insects die immediately after their eggs are 

 laid. Bees, wasps, and ants, however, which 

 live in society, and labor together for the com- 

 mon good of their communities, continue much 

 longer in the adult state. 



In winged or a(Mt insects, tvi'o of the trans- 

 verse 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, tlie second or middle por- 

 tion of the thorax, or chest, and the third or hind- 

 most the abdomen, or hind-body. In some wing- 

 less insects these three portions are also to be 

 seen ; but in most young insects, or lan'a;, the 

 body consists of the head, and a series of twelve 

 rings of segments, the thorax not being dis- 

 tinctly separated from tho hinder part of the 

 body, as may be perceived in caterpillars, grubs, 

 and magsots. 



The eyes of adult insects, though apparently 

 two in number, are compound, cacli consisting 

 of a great number ofsingle eyes closely united to- 

 gether, and uicapable of being rolled in their 

 sockets. Such also are the eyes of the larvs, 

 and of the active pupae of those insects that un- 

 dergo 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 com- 

 pletely ti-ansfonning larv», are not compounded, 

 but consist of five or six eyelets clustered to- 

 gether, without touching, on each side of the 

 head ; some, however, s»ch as maggots, are to- 

 tally blind. Near to the eyes are two jointed 

 members, named anfcnna, 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 antennffi are very short in larvas, and of va- 

 rious sizes and forms in other insects. 



The mouth of some insects is made for biting, 

 that of others ior taking food only by suction. 

 In biting insects the parts of the mouth, wliich 

 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 joint- 

 ed members, called palpi or feelers, vvliereof 

 two belong to the lower lip, and one or two to 

 each of the lower jaws. Tiio mouth of sucking 

 in.sects consists essentially of these same parts, 

 but so difierent in their shape and in the pur- 

 poses for which they are designed, that the re- 

 semblance between them and those of biting 

 insects is not easily recognized. Thus the jaws 

 of caterpillars are transformed to a spiral suck- 

 ing tube in butterflies and moths, and those of 

 maggots to a hard proboscis, fitted for piercing. 

 as in the muskcto and horse fly. or to one of soft- 

 er consistence, and ending with fleshy lips for 

 lapping, as in common flies ; while in bugs, 

 plant-lice, and some other insect.s resembling 

 them, the parts of the mouth undergo no essen- 

 tial change from infancy to the adult state, but 

 (901) 



are formed into a long. hard, and jointed beak, 

 bent under the breast when not in use, and de- 

 signed only for making punctures and drawing 

 in liijuid nourishment. 



The parts belonging to the thorax are the 

 wings and the legs. The former are two or 

 four in number, and vary gi-eatly in form and 

 consistence, in the situation of the wing-bones 

 or veins, as they are generally called, and in 

 their position or the manner in which they are 

 closed or folded when at rest. The under-side 

 of the thorax is the breast, and to this are fixed 

 the legs, which are six in number in adult in- 

 sects, and in the larvaj and pupae of those that 

 are subject only to a partial transformation. The 

 parts of the legs are the hip-joint, by which the 

 leg is fastened to the body, the thigh, the shank 

 (tthia), and the foot, the latter consisting .some- 

 times of one joint only, more often of two 

 three, four or five pieces {farsi), connected 

 end to end, like tlie joints of the finger, and 

 armed at the extremity with one or two claws. 

 Of the larvip that undergo a complete trans- 

 formation, maggots and some others are des- 

 titute of legs ; many grubs have six, namely 

 a pair beneath the under-side of the first three 

 segments, and sometimes an additional flesliy 

 prop-leg under the hindmost extremity: cat- 

 erpillars and false caterpillars have, besides the 

 six true legs attached to the first three rings, 

 several fleshy prop-like legs, amounting some- 

 times to ten or sixteen in number, placed in 

 pairs beneath the other segments. 



The abdomen or hindmost, and. as to size, the 

 principal part of the body, contains the organs 

 of digestion, and other internal parts, and to it 

 also belong the piercer and the sting ^^•ith which 

 many winged or adult insects are provided. 

 The piercer is sometimes only a flexible or a 

 jointed tube, capable of being thrust out of the 

 end of the body, and is used for conducting the 

 eggs into the crevices or holes where they are 

 to be laid. In some other insects it consists of 

 a kind of scabbard, containing a central borer, 

 or instruments like saws, designed for making 

 holes wherein the eggs are to be inserted. The 

 sting, in like manner, consists of a sheath en- 

 closing a sharp instrument for inflicting wounds, 

 connected wherewith in the inside of the body- 

 is a bag of venom or poison. The parts belong- 

 ing to the abdomen of larvae are various, but are 

 mostly designed to aid them in their motions, or 

 to provide for their respiration. 



An English entomologist has slated, that, on 

 an average, there are six distinct insects to one 

 plant. This proportion is probably too great 

 for our country, where vast tracts arc covered 

 with forests, and the other original vptretable 

 rares .still hold possession of the soil. There are 

 above liOO flowering jilants in Massachusetts, 

 and it will be within hounds to estimate the 

 species of in.sects at 4800. or in the proportion 

 of four to one plant. To facilitate the .«tudy of 

 such an immenso number, some kind of classi- 

 fication is necessary : it w-ill be useful to adopt 

 one, even in describing the few species now be- 

 fore us. The basis of this classific.ition is found- 

 ed upon the structure of the mouth, in the adult 

 state, the number and nature of the wings, and 

 the transformaticni.s. The first great divisions 

 are called orders, of which the following seven 

 are very generally adopted bj- naturalists. 



It appears to us that every intelligent farmer 

 would find the above-named Report a valuable 

 acquisition to his library. On no subject con- 



