MEANS OF DEFENCE OF INSECTS. 419 



smoke, attended by a very disagreeable scent, is seen to proceed from its 

 anus, which immediately stops the progress of its assailant : when it has 

 recovered from the effect of it, and the pursuit is renewed, a second dis- 

 charge again arrests its course. The bombardier can fire its artillery twenty 

 times in succession if necessary, and so gain time to effect its escape ; and 

 what is still more remarkable, Mr. Holme found that by pressing the abdo- 

 men near the anus, the discharges may be produced after death. In this 

 way two specimens which had been dead eighteen hours gave, one fifteen, 

 and the other nineteen discharges before being exhausted, and he even 

 obtained explosions from some specimens which had been dead four days ; 

 but most of these, along with the noise, discharged a black grainy fluid 

 without smoke. 1 Another species (B. displosor) makes explosions similar 

 to those of B. crepitans : when irritated it can give ten or twelve good dis- 

 charges ; but afterwards, instead of smoke, it emits a yellow or brown fluid. 

 By bending the joints of its abdomen it can direct its smoke to any parti- 

 cular point. M. Leon Dufour observes that this smoke has a strong and 

 pungent odour, which has a striking analogy with that exhaled by nitric 

 acid. It is caustic, reddening white paper, and producing on the skin the 

 sensation of burning, and forming red ,spots, which pass into brown, and 

 though washed remain several days. 2 This burning sensation, M. Lacor- 

 daire informs us, when arising from the discharges of the large exotic 

 species, is so painful, that he has often been obliged to let those which he 

 had taken escape. The same power of emitting explosions, as a means of 

 defence, is found also in some other coleopterous species, as in those of 

 the genus Paussus, according to M. Payen, who had an opportunity of 

 studying their habits in the isles of Sunda and the Moluccas 3 ; in those of 

 Cerapterus according to Mr. MacLeay 4 ; and in those of Qzcena in a slight 

 degree, according to M. Lacordaire. 



Another expedient to which insects have recourse, to rid themselves of 

 their enemies, is the emission of disagreeable jtfw'ck. These, some discharge 

 from the mouth ; others from the arms ; others again from the joints of 

 the limbs and segments of the body ; and a few from appropriate organs. 



You have doubtless often observed a black beetle crossing pathways 

 with a slow pace, which feeds upon the different species of bedstraw 

 (Galium), called by some the bloody-nose beetle (Timarcha tenebricosa). 

 This insect, when taken, usually ejects from its mouth a clear drop or two 

 of red fluid, which will stain paper of an orange colour. The carrion- 

 beetles (Silpha and Necrophorus), as also the larger Carabi, defile us, if 

 handled roughly, with brown fetid saliva. Mr. Sheppard having taken one 

 of the latter (C. violaceus), applied it in joke to his son's face, and was 

 surprised to hear him immediately cry out as if hurt : repeating the ex- 

 periment with another of his boys, he complained of its making him 

 smart : upon this he touched himself with it, and it caused as much pain 

 as if, after shaving, he had rubbed his face with spirits of wine. This he 

 observed was not invariably the case with this beetle, its saliva at other 

 times being harmless. Hence he conjectures that its caustic nature, in the 

 instance here recorded, might arise from its food ; which he had reason to 



1 Trans. Ent. Soc. Lond. ii. proc. vii. 



2 Ann. du Mm. xviii. 70. 3 Lacordaire, Introd. a VEntom. ii. 56. 

 * Westwood, Mod. Classif. of Ins. i. 151. 



2 



