MEANS OF DEFENCE OF INSECTS. 213 



milky fluid, the smell of which, De Geer observes, is al- 

 most insupportable s being inexpressibly strong and pene- 

 trating. These drops proceed at the same instant from 

 all the eighteen scent-organs; which forms a curious 

 spectacle. The insect, however, does not waste this pre- 

 cious fluid : each drop instead of falling, after appearing 

 for a moment and dispensing its perfume, is withdrawn 

 again within its receptacle, till the pressure is repeated, 

 when it reappears*. 



I shall now introduce you to the true counterparts of 

 the skunk, which explode a most fetid vapour from the 

 ordinary passage. I have lately hinted that the scent of 

 many Eutrechina is thus emitted. Anchomenus prasinus, 

 a beetle of this tribe, combats its enemies with repeated 

 discharges of smoke and noise : but the most famous for 

 their exploits in this way are those, which on this ac- 

 count are distinguished by the name of bombardiers 

 (Brachinus), The most common species (B. crepitans), 

 which is found occasionally in many parts of Britain, 

 when pursued by its great enemy, Calosoma Inquisitor, 

 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 ef- 

 fect its escape. Another species ( B. Displosor] makes ex- 

 plosions similar to those of B. crepitans : when irritated 



3 De Geer, v. 291. Compare Ray's Letters, 43. See PLATE XVI II. 

 FIG. 1. 



R 2 



