BEETLES 75 



Hydrophilus piceus the " harmless " water-beetle of 

 the aquarium is one of the largest British beetles. 

 When submerged, this insect carries a kind of breast- 

 plate of air, which is held in place by velvety tracts on 

 the underside of the body. It replenishes this supply 

 periodically by dragging down small air-bubbles with 

 its antennae, the terminal joints of which are broad and 

 hairy, and serve as little scoops. Although the adults 

 feed chiefly on vegetable matter, the larvae attack 

 other insects, and are very voracious. 



The family Silphidce includes more than one hundred 

 British species, which vary considerably in size and 

 form. They have straight, clubbed antennae, which 

 are usually composed of eleven joints. Most of them 

 feed on decaying animal or vegetable matter. The 

 sexton-, or burying-beetles, of the genus Necrophorus 

 are familiar examples. So also are the flat-looking 

 members of the genus Silpha, which are mostly carrion- 

 feeders, though one or two species are known to eat 

 the leaves of living plants. 



In the great family of the rove-beetles, or " cock- 

 tails," 1 the elytra are very short, covering only a 

 small part of the abdomen. The antennae are 

 moderately long, very gradually thickened towards the 

 tip, and have usually eleven joints, but sometimes ten 

 or even nine. The " devil's coach-horse" 2 is the best 

 known example ; but there are about 800 British 

 species, most of them very small. Many fly freely, 

 and cause annoyance during the summer months 

 by getting into our eyes when they are called 

 " flies." The larvae are very similar in appearance to 

 those of ground-beetles, but may be distinguished by 

 their one-clawed tarsi. Members of this family 

 1 Staphylinidcs, 2 Ocypusolens. 



