BEETLES 199 



Family : Gyrinida WHIRLIGIG BEETLES. 



These are the beetles so often seen on the surface of ponds, describing 

 circles in company with others. When disturbed, they dive below for safety. 

 They have an inner bladder at the end of the abdomen. They also possess 

 curious divided eyes, making four in all two on the upper, and two on the 

 lower surface of the head. They are thus able to see below the surface and 

 into the air as well. 



G. natator (Fig. 52). About J inch ; shining blue-black above, and black 

 beneath ; legs red. 



Deronectus depressus (Fig. 53). Tawny brown, with black pattern on the 

 elytra, in which are four tawny spots. Found on water weeds. 



Sub-order ii. CLAVICORNIA. 



This sub-order, as the name (clava, " club " ; cornu, " horn ") indicates, 

 contains beetles with knobbed or clubbed antennae, though in some cases the 

 clubbing is not very marked. Their legs are clumsy and small, for they do 

 not seek safety by flight, but when disturbed feign death, either by rolling 

 up or remaining motionless. They feed on carrion or dung. Some thirty 

 families are included under this heading. 



Family : Hydrophilidce. 



Distinguished from other water beetles by their method of swimming, 

 which is not by " rowing," but kicking their legs alternately. They live at 

 the bottom of standing water, feeding on vegetable matter. 



Hydrophilus piceus (the Great Water Beetle). You will be fortunate 

 if you find this species, for it is rare and local chiefly in the fens and round 

 London. There is no difficulty in identifying it, for it is the largest water 

 beetle, and of a shiny black. The female lays her eggs in a shining silvery 

 cocoon, which floats on the surface. 



Hydrobius fuscipes (Fig. 54). Black ; elytra many-grooved. Common 

 in stagnant water at the roots of plants. 



Philhydrus maritima (Fig. 55). Coppery brown. Found in stagnant water. 



Berosus affinis (Fig. 56). Head black ; thorax a dark copper ; elytra 

 almost black, with some dark brown shading. 



Helophorus aquaticus (Fig. 57). A similar species, but slightly larger. 

 Dark brownish yellow. Common on the edge of stagnant pools. 



Ochthebius pygmaus. Pale brown; very common, but very small; no 

 bigger than a pin's head. Found in water, under stones, and on decaying 

 vegetation. 



Cyclonotum orbicular e (Fig. 59). Shining black ; hemispherical body. 

 Not uncommon. 



