SHEATH-WINGED INSECTS 239 



signify 'diver' and 'water-lover' respectively, both 

 frequent the waters of deep ponds, of ditches, and of 

 pools. With their legs flattened out like oars, their 

 very smooth bodies, arched above and keel-shaped 

 below, they are first-rate swimmers and divers. It 

 is a feast for the eye to follow the graceful agility 

 of their oars when they row calmly on the surface 

 or plunge beneath it. 



"At the least alarm they dart quickly to the bed 

 of the pond and take refuge amid the water plants. 

 On the instant of diving their belly is seen to flash 

 like a plate of polished silver. The reason of this 

 borrowed sheen is found in a thin layer of air that 

 they carry with them adherent to the belly. With 

 this supply they will have air to breathe until, all 

 danger past, they ascend again to the surface. 



"In the matter of costume these two master-swim- 

 mers are of modest appearance. Both are of a very 

 somber olive green, but in addition the dytiscus 

 wears faded gold lace on its sheaths. If the pond 

 dries up or ceases to please them, they can quickly 

 betake themselves to another — not on foot, for their 

 flattened legs, excellent as oars, are worthless in 

 walking, but by flight, with the help of their mem- 

 branous wings, ordinarily hidden under the sheaths, 

 where the water cannot reach them. 



"In old oak trees the larva of the capricorn-beetle, 

 another ravager of forests, leads much the same kind 

 of life as does the grub of the stag-beetle. Large in 

 size, all black with gleams of chestnut, this insect is 

 remarkable for its jointed horns, which are longer 



