THE GIANT WATER-BUGS. 1041 



Family XXXVIII. BELOSTOMATID^E Leach, 1815, 123. 

 The Giant Water-bugs. 



Large or very large, dull brown, oval or oblong-oval, subde- 

 pressed aquatic Heteroptera having the head subconical, longer 

 than the width across the eyes, declivent in front ; eyes large, 

 projecting backward over front angles of pronotum ; ocelli ab- 

 sent ; beak stout, 3-jointed, reaching or slightly surpassing 

 front coxae; antennas very short, 4-jointed, the two middle 

 joints more or less pectinate, in repose concealed beneath the 

 eyes ; pronotum trapezoidal with a transverse impressed line 

 behind its middle, hind margin subtruncate, front one feebly 

 sinuate ; scutellum large, flat, triangular, its apex acute ; elytra 

 entire, covering the abdomen, the usual divisions distinct ; legs 

 short, front ones prehensile, their coxae short, femora stout, 

 usually grooved for the reception of the tibiae, front tarsi 2- 

 jointed, ending in a single long sharp claw; middle and hind 

 legs fitted for swimming, their tibiae and tarsi flattened, the 

 edges in Benacus and Lethocerus with a dense fringe of hairs, in 

 Belostoma armed also with setae, the tarsi with two claws ; abdo- 

 men with sides furnished with a broad stripe of appressed silky 

 yellowish hairs and apex with a pair of short retractile strap- 

 like appendages which, in repose, are usually concealed ; ven- 

 trals each appearing as if composed of three pieces, viz., a flat 

 subquadrate one each side and a much wider median one which 

 is strongly keeled. 



In bulk of body this family comprises the largest of our 

 Heteroptera some of the tropical South American species 

 reaching a length of more than four inches. All are predatory, 

 feeding on aquatic insects, young fish, tadpoles and other water- 

 dwelling creatures. In the nymphal stages the front tarsi are 

 furnished with two long claws, in the adult with but one. Dur- 

 ing the mating season they fly from one pool or body of water 

 to another. When electric street lights were first installed our 

 larger species were attracted to them by hundreds and for the 

 first time the average human learned that such bugs were deni- 

 zens of the earth. To them he gave the name of "electric light 

 bugs," and their uncouth shape and sprawling motions, when 

 on the ground benath the lights, usually caused him to regard 

 them with a "holy terror." They are, however, harmless, but 

 when picked up incautiously can inflict a severe wound with 

 their stout beak. This is very painful for a time, but seldom 

 produces a swelling or numbness. 



