224 MEANS OF DEFENCE OF INSECTS. 



The powers of annoyance^ by means of their hairs, with 

 which the moth of the fir, and the procession-moth, be- 

 fore noticed a , are gifted, are doubtless a defensive ar- 

 mour to them. Madame Merian has figured an enor- 

 mous caterpillar of this kind, which unfortunately she 

 could not trace to the perfect insect, by the very touch 

 of which her hands, she says, were inflamed, and that 

 the inflammation was succeeded by the most excruci- 

 ating pain 5 . The vesicatory beetles, likewise, (Cantharis 

 vestcatoria, &c.) are not improbably defended from their 

 assailants by the remarkable quality, so useful to suffer- 

 ing mortals, that distinguishes them. 



Your own observation must have proved to you, that 

 insects often escape great perils, from the crush of the 

 foot, or of superincumbent weights, by the hardness of 

 the substance that covers great numbers of them. The 

 elytra of many beetles of the genus Hister are so nearly 

 impenetrable, that it is very difficult to make a pin pass 

 through them ; and the smaller stag-beetle (Dorcus pa- 

 rallelopipedus] will bear almost any weight the head 

 and trunk forming a slight angle with the abdomen 

 which passes over it upon the ground. Other insects 

 are protected by the toughness of their skin. A re- 

 markable instance of this is afforded by the common fo- 

 rest-fly (Hippobosca equina\ which, as was before ob- 

 served , can scarcely be killed by the utmost pressure of 

 the finger and thumb. 



a VOL. I. p. 130. 



b Insect. Surinam, t. 57. Two different species of caterpillars ap- 

 parently related to this of Madame Merian were in the late Mr. 

 Francillon's cabinet, and are now in my possession 



c VOL. I. p. 149. 



