INSECTS. 



worms {Vermes, Liu.) by always hav- 

 ing feet in their perfect state, as the 

 beetle, butterfly, etc. Worms crawl 

 upon their bellies, and have no feet, 

 as the earth-worm, slug, snail, &c. 

 The generality of insects have only 

 six feet {Hexapods) ; but some few, 

 generally called by this name, have 

 a great many, as the wood-luuse, cen- 

 tipede, &c. 



" Nearly all insects are oviparous ; 

 that is, produced from an egg. Tiiese 

 eggs are seldom found singly. Tliose, 

 of some species, are hatched in a few 

 days, while others remain during the 

 winter, and the young do not come 

 forth until the season at which the 

 leaves of the plants upon which they 

 feed begin to e.\pand. 



" The second state of the insect is 

 called the eruca, or larva. Caterpil- 

 lars are those larva; which are ex- 

 posed, and feed upon leaves and 

 plants. The larva; of beetles usual- 

 ly live in the earth, in the trunks of 

 trees, or in the substance upon which 

 they feed ; they are generally of a 

 whitish colour, thick and clumsy in 

 form, and are called grubs ; while 

 the name of maggots is usually given 

 to the larva; of flies, bees, ants, &c., 

 all of which live in the same confined 

 state as those of beetles. It is in 

 this stage of existence that insects 

 are most voracious, and, consequent- 

 ly, most destructive to plants. 



" \\hen the larva has attained to its 

 full size, it changes into the pupa or 

 chrysalis state. This is done in dif- 

 ferent situations, according to the 

 tribes to which they belong. The 

 chrysalis of butterflies are naked, and 

 are either suspended or attached to 

 trees, branches, walls, &ic. Those 

 of moths are either concealed in a 

 case, like the cocoon of the silkworm, 

 or the caterpillar undergoes its change 

 in the earth. The period in which 

 insects remain in this state varies 

 according to the species ; but in most 

 cases they are inactive and torpid. 



•' The imago, or perfect insect, is 

 produced from the ciirysalis, and is 

 t!ie only state in which all its parts 

 and members are fully developed. 

 The appearance and economy of per- 



feet insects, in genera!, is totally dif- 

 ferent from those of the larva; and 

 pupae, and it is only in its final stage 

 of existence that the species can be 

 ascertained. With the exception of 

 such insects as form the aptera of 

 Linnaeus, all others are furnished with 

 wings, either four or two in number. 

 Some few exceptions, however, oc- 

 cur to this rule ; the female of the 

 glow-worm and of some few moths 

 are apterous, while many beetles (al- 

 though furnished with hard winged 

 cases) are destitute of real wings. 

 The body is divided into a head, tho- 

 rax or chest, and abdomen : the head 

 sustains a pair of antennae, resem- 

 bling horns, two eyes, often very 

 compound ; the parts of the mouth 

 are a labium, labrum, mandibles, and 

 maxilla;, or jaws ; to the latter are 

 attached the organs of feeling (palpi). 



"The duration of insects is ex- 

 tremely variable : the greatest pro- 

 portion appear to be annuals, emer- 

 ging from the egg and passing through 

 the three stages of their existence 

 within the space of a year. But there 

 are a great number of species, particu- 

 larly among the beetles, which pass 

 three, and even four years in the cat- 

 erpillar state ; and instances are on 

 record of beetles remaining in timber 

 from ten to fifteen years. The greatest 

 proportion of moths are biennial, pass- 

 ing the winter in the chrysalis state, 

 and closing their existence in the suc- 

 ceeding summer. The transitory life 

 of the ephemera is proverbial ; the 

 perfect insect, indeed, exists but for 

 a day, and seems born only to con- 

 tinue its species, yet in the larva state 

 it enjoys a life of one, two, or even 

 three years. 



" Arrangement or Classification of 

 Insects. — AH insects may be divided 

 into two groups : 1. Apterous insects, 

 having either no metamorpho^s, or 

 only that kind of it the tendency of 

 which is confined to the increase of 

 the number of feet : these, as their 

 name implies, are destitute of wings. 

 2. True insects, or those whose met- 

 amorphosis has a tendency to give 

 wings to the perfect or image state, 

 but never more than six feet. 



421 



