ENTOMOLOGIST AND BOTANIST. 



233 



pilosis, the larvas and perfect insects usually 

 feed together, and it niiglit he thought impos- 

 sible, at first sight, to tell which are the more 

 destructive. But when we consider the import- 

 ant fact to wJiich we have hei'ore adverted, that 

 the Avhole growth of insects takes place in tlie 

 larva state, we must conclude that even in these 

 cases, the principal damage must be oflected 

 whilst the insects are iu the preparatory stage. 

 If to this we add that one of the most destructive 

 orders of insects, namely, the Lepidoptera, com- 

 mit all their havoc in the larva form of cater- 

 pillars, we shall be able to form some estimate 

 of the preponderance of damage effected by in- 

 sects in the larva state. 



Let us now inquire if larvie exliibit any char- 

 acters by which we can so classify them as to 

 determine to what orders and families they will 

 respectively belong wheu they shall have attained 

 their perfect state. 



The difficulty which has attended all attemiits 

 to classify lai-vje upon their own characters, and 

 at the same time preserve their relationship to 

 their i-espective imagines, strongly exliibits tlie 

 comparative inferiority or degradation of the 

 larval state. We can indeed classify larvoe into 

 what seem to be natural groups, founded upon 

 their most important and prominent characters ; 

 but wheu we come to put opposite to them, in 

 parallel series, the perfect insects which these 

 lai'vse produce, we are astonished to find that 

 every vestige of relationship is lost. Take, for 

 example, the classification of larvce by Kirby and 

 Speuce. These authors arrange larvie iu five 

 principal groups. The first group produces, 

 wheu arrived at the perfect state, a hetei'ogene- 

 ous mixture of Coleoptera, H)'menoptera and 

 Diptera. The second group produces Diptera 

 only. In the third, two of the most remote 

 orders of insects, the Coleoptera and Neuroptera 

 are brought into juxtaposition. In the fourth, a 

 part of the Tipulidae are separated from the rest 

 of their family, and from the Dipterous order, 

 and associated with the Miero-Lepidoptera. And 

 in the fifth group, Coleoptera, Hymenoptera and 

 Lepidoptera are indiscriminately associated to- 

 gether. 



Still the practical question remains whether 

 any general rules can be established, by whicli 

 we can know wliat form the noxious larvse wc 

 meet witli, will ultimately assume. 



In order to understand what follows, it is 

 necessary to state that larv:? have legs of two 

 kinds : first, the true legs, representing the legs 

 of the perfect insect, which are comparatively 

 firm, conical, and jointed, and, when present, are 

 almost always six in number, and attached to 



the first three segments of the body. Secondly, 

 the spurious legs, or prologs, wliich are short, 

 tliick, muscular and uuarticulatcd, varying in 

 number from two to sixloen, and attached to one 

 or more of the eight last segments. 



1st. Oeneralization. All larvaj generally 

 known as Caterpillars, and distinguished by 

 having both legs and prologs, produce cither 

 Lei)idoi)tcra, or Saw-flies in the order Hymen- 

 optera ; and the lan^a' of the Saw-flics are dis- 

 tinguished from those of the Lcjjidoptera by 

 having more than five pairs of prolegs ; and by 

 having only two eyes, whilst the true caterpillars 

 have fen or twelve, and also by their habit of 

 rolling tliemselves into a spiral coil. 



L'd. As a general rule, hairy caterpillars pro- 

 duce moths, whilst spiny or naked ones produce 

 butterflies or spliinges. The rule may be more 

 accurately stated thus : All densely haired cater- 

 pillars produce moths, but all tlic larv* of moths 

 are not hairy. The cateri)illars of the butterflies 

 and spliinges are either naked or ornamented 

 with spines, or with very short or scattered 

 hairs. 



3d. Wood-boring lai-va; belong mostly to the 

 Coleoptera; but also to a few families of the 

 Lepidoptera, namely, the ^geridte, the Hepi- 

 alida', and a few exceptional Tortricidte. The 

 larviB of the Lepidoptera can always be distin- 

 guished from those of the Coleoptera, by the 

 presence of prolegs on the intermediate seg- 

 ments. A few Coleopterous larvae have one pair 

 of prolegs on the anal segment, but more gener- 

 ally only one such leg. 



■ith. All leaf-sucking larva; belong to the order 

 Hemiptera (including the Homoptera). 



."Jth. All leaf-gnawing larvoe, excepting grass- 

 hoi)pers, and the caterpillars above treated of, 

 belong to one tribe of Coleoptera, distinguished 

 by the title of Phyllophaga, or Leaf-eaters, and 

 comprising the four families Crioceridse, Galer- 

 iicidie, Cassididie, and Chrysomelidse. These 

 larv*, moreover, can generally be identified by 

 their sliort, wrinkled forms, their sluggish mo- 

 tions, and some of tliem by the singular habit of 

 protecting their bodies by their own excrement. 



(ith. All laiTiB found underground, excepting 

 those which enter it only for the purjiose of 

 undergoing their transformations, are divisible, 

 according to their habits, into two sections. 

 First, the subterranean larva;, ])roperly so called, 

 which live under ground, and feed upon the 

 roots of plants ; and, secondly, those which sub- 

 sist above ground, but burrow into it, when not 

 feeding, for the purpose of concealment. True 

 subterranean larva; are found in the orders Cole- 

 optera, Hemiptera, Homoptera, and Diptera. 



