458 MEANS OF DEFENCE OF INSECTS. 



it dart forth these menacing catapuUs, apprehending they might be poi- 

 sonous organs, his courage failed him. At length, without touching the 

 monster, he ventured to cut off the twig on which it was, and let it drop 

 into a box !^ The caterpillar of tfie gold-tail moth (^Porthesia chrysorhaa) 

 has a remarkable aperture, which it can open and shut, surrounded by a 

 rim on the upper part of each segment. This aperture includes a little 

 cavity, from which it has the power of darling forth small flocks of a cot- 

 tony matter that fills it.^ This manoeuvre is probably connected with our 

 present subject, and employed to defend it from its enemies. It also 

 ejects a fluid from its anus. 



There is a moth in New Holland, the larva of which annoys its foes 

 in a different way : from eight tubercles in its back it darts forth, when 

 alarmed, as many bunches of little stings, by which it inflicts very painful 

 and venomous wounds.^ 



The caterpillar of the moth of the beach (^Staurojpus Fagi), called the 

 lobster, is distinguished by the uncommon length of its anterior legs. Mr. 

 Stephens, an acute entomologist, relates to me that he once saw this 

 animal use them to rid itself of a mite that incommoded it. They are 

 probably equally useful in delivering it from the ichneumon and its other 

 insect enemies. Dr. Arnold has made a curious observation (confirmed 

 by Dr. Forsstrom with respect to others of the genus) on the use of the 

 long processes or tails that distinguish the secondary wings of Thecla 

 larbas. These processes, he remarks, resemble antennae, and when the 

 butterfly is sitting it keeps them in constant motion ; so that at first sight 

 it appears to have a head at each extremity ; which deception is much 

 increased by a spot resembling an eye at the base of the processes. 

 These insects, perhaps, thus perplex or alarm ttieir assailants. — Goedart 

 pretended that the anal horn with which the caterpillars of so many hawk- 

 moths (^Sphingidia) are armed, answers the end of a sting instilling a dan- 

 gerous venom : but the observations of modern entomologists have proved 

 that this is altogether fabulous, since the animal has not the power of mov- 

 ing them."* Their use is still unknown. 



Whether the long and often threatening horns on the head, the thorax, 

 and even elytra, with which many insects are armed, are beneficial to 

 them in the view under consideration, is very uncertain. They are fre- 

 quently sexual distinctions, and have a reference probably rather to 

 sexual purposes and the economy of the animal, than to any thing else. 

 They may, however, in some instances deter enemies from attacking 

 them, and therefore it was right not to omit them wholly, though 1 shall 

 not further enlarge upon them. Their mandibles or upper jaws, though 

 principally intended for mastication, — and in the case of the Hymenop- 

 tera, as instruments for various economical and mechanical uses, — are 

 often employed to annoy their enemies or assailants. I once suffered 

 considerable pain from the bite of the common water-beetle (^Dytiscus 

 marginalus), as well as from that of the great rove-beetle {Goerius olens) ; 

 but the most tremendous and eff*ectual weapon with which insects are 

 armed — though this, except in the case of the scorpion, is also a sexual 

 instrument, and useful to the females in oviposition — is their sting. With 



' 1. iv. 122. « Reaum. ii, 155, t. vii. f. 4—7. 



' Lewjn's Prodromus. * De Geer, i. 149. 



