ijooK VI : 



NOXIOUS INSECTS. 



1067 



others remain for several months. The eggs of many insects remain without being 

 hatched during the whole winter, and the young insects do not come forth from them 

 till the season at wliich the leaves of the vegetables on which they feed l)egin to expand. 

 6866. The insect in its second or caterpillar state {Jig. 749. ) has been usually known 



749 



by the name of eruca or larva, being a sort of masked form or disguise of the insect in its 

 complete state. The larvae of insects differ very much from each other, according to the 

 several tribes to which they belong ; those of the butterfly (Pajnlio) and moth [Phalcena) 

 tribes are generally known by the name of caterpillars ; those of the beetle (Scarabceus), 

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

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

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

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

 water-beetles {Dytiscus) are of very 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 are 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 liguslri,Jtg. 749 a) ; the cabbage birtterfly (Papilio brassica, b) ; the 

 turnip butterfly (P. 7inpi, c) ; gooseberry moth (Phalcena wavaria, d) ; the currant moth 

 {Ph. grossularia, e) ; the dragon fly {Libcllula virgo, f) ; the common chafer {Scarabceus 

 inelolonthay g) ; the phryganea rhombica fji) ; the frog-hopper {Cicada spu?naria, i\ ; and 

 the musca pumilionis (4). 



6867. IVhen the larva is about to change into the chrysalis or jmpa state (fig. 750.) 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 different 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 desti- 

 tute of legs ; but in the locust tribe it 

 differs very little from the perfect insect, 

 excep.t in not having the wings complete. 

 In most of the fly tribe it is perfectly oval, 

 without any apparent motion 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 ap- 

 pearance 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 

 examples of the chrysalis of various insects, wc give those of the beetle {Scarabceus 



