208 THE HARMONIES OF NATURE. 



assuming attitudes of a threatening or terrific character. A 



considerable number of insects 

 defend themselves by the secre- 

 tion of poisonous or foetid scents 

 or fluids. Thus many of the 

 tropical ants emit a corrosive 

 acid, which, infused into the wound 

 caused by their mandibles, pro- 



Caterpillar of Hawk-moth. dUC6S the m St excruciating pain. 



Woe to the naturalist who, ig- 

 norant of the fact, endeavours to break off a shoot of the Tri- 

 plaris, or merely knocks against this tree, whose hollow branches 

 harbour one of the most ferocious ants, for thousands will in- 

 stantly issue from small round lateral openings in the plant, and 

 fall upon him with fury ! The touch of a red-hot iron is not 

 more painful than their bite, and the inflammation and pain 

 last for several days after. 



But the most extraordinary insects possessing this species of 

 defence are the beetles called bombardiers. The most common 

 species (Brachinus cr^pifcms), when pursued by some formidable 

 enemy, seem 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, and this 

 immediately stops the progress of its assailant. When the latter 

 has recovered from the effects of this discharge, and the pursuit is 

 renewed, a second in like manner arrests its course. The little 

 artilleryman can fire his gun twenty times in succession, if 

 necessary, and so gain time to effect his escape. The smoke 

 has a strong and pungent odour, very similar to that of nitric 

 acid ; it is caustic, and produces on the skin the sensation of 

 burning. Other insects, to whom such energetic means of defence 

 have been denied, have recourse to concealment for their safet}^. 

 Thus the small aquatic beetles creep under the mud, to be 

 secure, while feeding, from the larger predaceous sorts which 

 surround them. The Keduvius personatus, a species of bug, 

 hides itself under a thick coat of dust, which answers the double 

 purpose of stratagem and protection ; and some of the tortoise- 

 beetles have the still more singular custom of sheltering them- 

 selves under a canopy affixed to their tail, and formed of their 

 own excrement ; this they elevate in the air, bringing it over 



