PROTECTIVE COLORATION AND DEFENSIVE STRUCTURES OF LARV^S. 99 



raises the front half of its body from the ground and uses it as a kind 

 of whip-lash, throwing it from one side to the other with great 

 violence. When it walks, it moves with a slow and cautious tread, 

 its head trembling as if it had the palsy. All this is doubtless to 

 inspire fear in such enemies as might be tempted to attack it." 



The excretions of larvae are of considerable importance in forming 

 a means of defence. It is a very prevalent practice, amongst some 

 larvae, to eject from the mouth a fluid, usually, but not necessarily, 

 of a bright green colour, as soon as they are touched. This fluid is 

 secreted most freely among the Vanessids, Tortricids, Lasiocampids 

 and Geometrids, and its wide-spread occurrence points to it as an 

 effective weapon for their protection. 



Many Sphingid (and other) larvae — Smerinthm popidi, Macroglossa 

 stellatarum, etc. — have a habit, when quite full-grown, of " licking " 

 themselves on the dorsum, and, whilst so doing, they spread a fluid 

 over the surface of the back. It has been observed that the "licked" 

 portions of the body are those that change colour, and the fluid may 

 nave some action on the chitin, that brings about this change. If so, 

 it is a very useful means of protection, for, at this time, the. usually 

 green Sphingid larva? leave the green leaves of their food-plant, and 

 crawl for a considerable distance over the surface of the ground (where 

 their normally green colour would be exceedingly conspicuous) to find 

 a suitable place for pupation. It has been suggested, however, that 

 the fluid is used as a protection against ichneumons, the larvae being, 

 just previous to pupation, in a most helpless condition. 



So far as our observations go, this fluid appears to be of the same 

 nature as that used by various larvae (Eriogaster lanestris, etc.), for the 

 coloration of their cocoons. The fluid comes from the alimentary 

 canal, and appears to contain a modified form of chlorophyll. The 

 fact that those portions of the body on which the fluid is rubbed, 

 turn red, or purple, or brown, suggests that the change may be due to 

 the oxidation of the chlorophyll-extract present in the fluid. 



The inedible nature of hairs has been already remarked upon. 

 The spinose character of certain larval hairs is very marked, the main 

 shaft often bristling with numberless, minute, lateral points. These 

 hairs are very general in many families, the Anthrocerids, Liparids, 

 Arctiids, etc. Such hairs must produce great irritation if they enter 

 the epithelial lining of the alimentary canal of an entomophagous bird or 

 mammal. The effect of the urticating hairs of certain Liparid and 

 Lasiocampid moths is within the knowledge of every entomologist. 



Many larva?, notably those of the Liparids, have tussocks, or tufts 

 of these fine, spinose hairs, often so dense that the combined effects 

 of these hairs, if inadvertently swallowed, might be very serious. The 

 easy manner in which they can be pulled out also aids in disseminating 

 them if they once enter the mouth. When irritated, tussock-bearing 

 larva? usually bend themselves so as to throw up prominently these 

 bristling tufts, and a hasty enemy finds its mouth filled with loose 

 hairs instead of the tasty morsel it had expected. Insect-eating 

 animals must undoubtedly learn, by experience, what is edible and 

 what is not, and a first attempt at a hairy larva is likely to be a last 

 with any tender-mouthed creature. Dozens of observers have noticed 

 the fact that various insect-eating birds and mammals have refused 

 hairy and spiny larva?, even when hungry. 



