428 



SCIENCE OF GARDENING. 



Part II. 



such as inhabit the water, are of a thick, clumsy form, called grubs. The larva? of the 

 locust, or grasshopper (Gryllus), do not differ very much in appearance from the com- 

 plete insect ; except being without wings. The larvae of flies (Musca), bees (Apk), &c. 

 are generally known by the name of maggots, and are of a thick short form. Those of 

 water-beetles (Dytiscus) are of highly singular forms, and differ, perhaps, more from that 

 of the complete insect than any other, except those of the butterfly tribe. Some insects 

 undergo no change of shape, but are hatched from the egg complete in all their parts, 

 and they undergo no farther alteration than that of casting their skin from time to time, 

 till they acquire the complete resemblance of the parent animal. In the larva state most 

 insects are peculiarly voracious, as in many of the common caterpillars. In their per- 

 fect state some insects, as butterflies,' are satisfied with the lightest nutriment, while others 

 devour animal and vegetable substances with a considerable degree of avidity. As an 

 example of the caterpillar state of some of the commoner insects, we may refer to that of 

 the privet-moth (Sphinx ligustri) (a) ; the cabbage-butterfly (Papilio brassica) (b) ; the tur- 

 nip-butterfly (P. napi) (c); gooseberry-moth (Phaleena wavaria) (d) ; the currant-moth 

 (Ph. grossularia) (e); the dragon-fly (Libellula virgo) (f) ; the common chafer (Scarabceus 

 melolonlha) (g) ; the phryganea rhombica (/*) ; the frog-hopper (Cicada sjrumaria) (i) ; and 

 the musca pumilionis (k). 



2228. When the larva is about to change into the chrysalis or pupa state ( Jig. 395) it ceases to 

 feed, and having placed itself in some quiet situation, lies still for several hours, and then, 

 by a sort of effort, it divests itself of its external skin, and immediately appears in the dif- 

 ferent form of a chrysalis or pupa ; in this state, likewise, the insects of different genera 

 differ almost as much as the larva;. In most of the beetle tribe it is furnished with short 

 legs, capable of some degree of motion, though very rarely exerted. In the butterfly tribe 

 it is destitute of legs; but in the locust 395 

 tribe it differs very little from the perfect 

 insect, except in not having the wings 

 complete. In most of the fly tribe it is 

 perfectly oval, without any apparent mo- 

 tion or distinction of parts. The pupa of 

 the bee is not so shapeless as that of flies, 

 exhibiting the faint appearance of limbs. 

 Those of the dragon-fly (Libellula) differ 

 most widely from the appearance of the 

 complete insect ; from the pupa emerges 

 the image or insect in its ultimate form, 

 from which it never changes, nor receives 

 any farther increase of growth. As ex- 

 amples of the chrysalis of various insects, 

 we give those of the beetle (Melolontha 

 vulgaris) (Jig. 395. a), papilio napi (b), 

 P. Io, (c), phalaena grossularia (d), Ph. 

 wavaria (e), tipula cornicina (/), phryganea rhombica (g), musca pumilionis, natural size 

 and magnified (h, h). 



2229. The sexes of insects are commonly two, male and female. Neuters are to be met 

 with among those insects which live in swarms, 

 such as ants, bees, &c. As examples of the 

 appearance of different insects in regard to 

 sex, we refer to the male, female, and neuter 

 ant (fig- 396 - a > b, c), and to the male or drone, 

 female or queen, and neuter or working bee 



2230. In duration, the majority of insects 

 are observed to be annual, finishing the whole 

 term of their lives in the space of a year or less, 

 and many do not live half that time ; nay, there 

 are some which do not survive many hours ; 

 but this latter period is to be understood only 

 of the animals when in their complete or ulti- 

 mate form, for the larvae of such as are of this 

 short duration have in reality lived a very long 

 time under water, of which they are natives ; 

 and it is observed, that water insects in general 

 are of longer duration than land insects. Some 



few insects, however, in their complete state, are supposed to live a considerable time, as 

 bees tor instance ; and it is well known that some of the butterfly tribe, though the major 

 part perish before winter, will yet survive that season in a state of torpidity, and again 



396 



