MEANS OF DEFENCE OF INSECTS. 423 



The caterpillar of the moth of the beach (Stauropus 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 pro- 

 bably 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 pro- 

 cesses 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, per- 

 haps, thus perplex or alarm their assailants. Goedart pretended that the 

 anal horn with which the caterpillars of so many hawk-moths ( Sphingidce) 

 are armed, answers the end of a sting, instilling a dangerous venom : but 

 the observations of modern entomologists have proved that this is altogether 

 fabulous, since the animal has not the power of moving them. 1 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 anything else. 

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

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

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

 principally intended for mastication, and in the case of the Hymenoptera, 

 as instruments for various economical and mechanical uses, are often 

 employed to annoy their enemies or assailants. I once suffered consider- 

 able pain from the bite of the common water-beetle (Dytiscus marginalis), 

 as well as from that of the great rove-beetle (Goerius olens); but the most 

 tremendous and effectual 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 ovipositiou is their sting. With this they keep 

 not only the larger animals, but even man himself, in awe and at a distance. 

 But on these I enlarged sufficiently in a former letter. 2 



These weapons, fearful as they are, would be of but little use to insects 

 if they had not courage to employ them : in this quality, however, they 

 are by no means deficient ; for, their diminutive size considered, they are, 

 many of them, the most valiant animals in nature. The giant bulk of an 

 elephant would not deter a hornet, a bee, or even an ant, from attacking 

 it, if it was provoked. I once observed a small spider walking in my 

 path. On putting my stick to it, it immediately turned round as if to 

 defend itself. On the approach of my finger, it lifted itself up and stretched 



1 De Geer, i. 149. 



2 Mr. MacLeay relates to me, from the communications of Mr. E. Forster, the 

 following particulars respecting the history of Mutiila coccinea, which from this 

 account appears to be one of the most redoubtable of stinging insects. The females 

 are most plentiful in Maryland in the months of July and August, but are never 

 very numerous. They are very active, and have been observed to take flies by 

 surprise. A person stung by one of them lost his senses in five minutes, and was 

 so ill for several days that his life was despaired of. 



BE 4 



