454 MEANS OF DEFENCE OF INSECTS. 



from all the eighteen scent-organs ; which forms a curious spectacle. The 

 insect, however, does not waste this precious fluid : each drop instead of 

 falling, after appearing for a moment and dispensing its perfume, is with- 

 drawn again within its receptacle, till the pressure is repeated, when it 

 re-appears.^ 



I shall now introduce you to the true counterparts of the skunk, which 

 explode a most fetid vapor from the ordinary passage, and combat their 

 enemies with repeated discharges of smoke and noise. The most famous 

 for their exploits in this way are those beetles which on this account are 

 distinguished by the name of bombardiers (Brachinus). The most com- 

 mon species {B. crepitans), which is found occasionally in many parts of 

 Britain, when pursued by its great enemy, Calosomn inqidsitor, seems at 

 first to have no mode of escape : when suddenly a loud explosion is heard, 

 and a blue 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 

 discharge again arrests its course. The bombardier can fire its artillery 

 twenty times in succession if necessary, and so gain time to eftect its 

 escape; and what is still more remarkable, Mr. Holme found that by 

 pressing the abdomen 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 dis- 

 charged a black grainy fluid without smoke.^ Another species (B. displo- 

 sor) makes explosions similar to those of B. crepitans : when irritated it 

 can give ten or twelve good discharges ; 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 particular point. M, Leon Dufour observes 

 that this smoke has a strong and pungent odor, which has a striking analogy 

 with that exhaled by the 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.^ This 

 burning sensation, M. Lacordaire informs us, when arising from the dis- 

 charges 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 Pnussus, according to M. 

 Payen, who had an opportunity of studying their habits in the isles of 

 Sunda and the Moluccas^ ; in those of Cerapterus according to Mr. Mac- 

 Leay^; and in those of Ozcena in a slight degree, according to M. Lacor- 

 daire. 



Another expedient to which insects have recourse, to rid themselves 

 of their enemies, is the emission of disagreeable fluids. These some dis- 

 charge from the mouth ; others from the anus ; others again from the joints 

 of the limbs and segments of the body ; and a k\y from appropriate 

 organs. 



* Ibid. V. 291. Compare Ray's Letters, 43. 



* Trans. Enf. Soc. Lond. ii. proc. vii. 



' Ann. dii Mm. xviii. 70. * Lacordaire, Introd. t VEntom. ii. 56. 



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



