24 INSECTS AT HOME. 



The Brachini may be identified by the very convex body, 

 and their palpi without the securiform terminal joint. The 

 Bombardier Beetle is reddish-yellow, with dull deep-blue 

 elytra. It is, however, a variable species, as are all, or nearly 

 all, of those in which green or blue is the prevailing colour, 

 and, though most specimens are blue, or blue-black, some are 

 deep blackish-green. It also varies greatly in size, some 

 specimens being not a quarter of an inch in length, and others 

 more than the third of an inch long. 



These Beetles love wet situations, especially when the water 

 is brackish, and hide under stones and in crevices, so that they 

 are seldom seen except by insect hunters. The banks of tidal 

 rivers are good hunting grounds for the searchers after 

 Brachini, such as the Thames, from Erith, or even Woolwich, to 

 its mouth. They are found in greatest numbers below Gfraves- 

 end, and ten or twelve may sometimes be seen under a single 

 stone, firing off their artillery when deprived of their shelter. 



The volatile fluid which produces such curious effects is 

 secreted in a little sac just within the end of the abdomen. 

 It is not only capable of repelling the larger Beetles by its 

 explosion and cloud of blue vapour, but is potent enough to 

 discolour the human skin when discharged against it, as many 

 have found who have captured Bombardier Beetles by hand. 

 Should it get within the eyelids, the pain and irritation pro- 

 duced resemble those which would be caused by a correspond- 

 ing amount of the strongest vinegar. 



The whole of the contents are not ejected at one discharge, 

 but there is sufficient to produce a series of explosions, each 

 perceptibly fainter than its predecessor. Even after the death 

 O'f the Beetle, the explosions may be produced by pressing the 

 abdomen between the finger and thumb. Even in our small 

 British species the phenomenon is very surprising, but there 

 are much larger species in hotter countries, which produce 

 much louder explosions, accompanied with quite a cloud of 

 vapour. Two British species of Brachinus are known to ento- 

 mologists. 



We come now to another family of Geodephaga, of which 

 we can but take one example. The Scaritidse, like the pre- 

 ceding family, are seldom seen in the open air, but, instead of 



