The Beetles of the Downs 



phaga called Brachinus crepitans (the detonating 

 Brachinus), Fig. 18, Plate IV. It is so named because 

 it has the power when disturbed, which it very occas- 

 ionally (and not invariably, as might be gathered from 

 some of the books) exercises, of ejecting from its body 

 a volatile fluid which vaporizes on contact with the 

 air with a slight explosion. Sometimes quite a number 

 of these beetles may be disclosed under one stone ; 

 they vary a good deal in size, but are usually about 

 8 mm. long, the head and thorax are rust-red, the 

 thorax longer than broad and narrowed behind with 

 a distinct groove down the centre, the elytra oval, 

 bluish or greenish-black and dull, which is due to the 

 fine pubescence with which they are covered, the legs 

 and antennae reddish. It will be noticed that the 

 elytra leave just the tip of the hind body or abdomen 

 exposed, which shows that Brachinus, like the Dromius 

 (Fig. 7, Plate III.), belongs to that division of 

 the Geodephaga known as Truncatipennes, of which 

 that point of structure, viz., that the elytra do not 

 quite cover the abdomen, is characteristic. There 

 are two other Brachini of which ancient and very 

 doubtful British records exist, but as none have been 

 captured for at least fifty years we need not take 

 them into consideration. 



Another beetle of rather striking appearance we are 

 likely to find under some of these loose stones, 

 and that is Badister bipustulatus (the two-spotted 

 Badister), Fig. 15, Plate IV. This is a moderate sized 

 insect about 5 mm. long, with a black head, a red 



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