hungerford: aquatic hemiptera, 135 



the "Veliinae of the Atlantic States," and also contributed to the biology of 

 two species of Microvelia. The writer has reared but one species in this 

 family, M. boreaUs. 



Genus MICROVELIA Westw. 

 The two species that have been reared in this country are M. americana 

 and M. horealis. The former about the largest and the latter the smallest 

 of the genus. Bueno has published the life history of the latter just 

 recently (Oct., 1917) in Ent. News. The WTiter reared this species in 

 the summer of 1916. 



Microvelia americana Uhl. 



Habitat. Bueno says: "Many an entomologist when drinking from a 

 field or roadside spring has noticed the tiny black, silver-spangled insects 

 that detach themselves from the stones forming the basin, and run across 

 the surface, or glide out from the side and swiftly curve in to their former 

 resting places. This is .1/. amencana Uhl. It is to be found on the banks 

 of any body of water, moving or still. Where the walls of the spring or 

 the bank of the stream or pond are more or less vertical, they perch a 

 little above the water. But on shelving or sloping banks they wander 

 about over the mud or pebbles, seeking their prey, leaving the shore only 

 when alarmed or disturbed. They also conceal themselves under the 

 overhanging banks of streamlets, as observed by Uhler in Maryland, and 

 the writer in New Jersey. . . ." 



Hibernation. They hibernate in colonies beneath the overhanging 

 banks of little streams in the middle states. (Uhler.) 



Mating. Mating has been described in some detail by Bueno. (See 

 Can. Ent., p. 180, 1910.) 



Oviposition. The eggs are white oval bodies, and are placed singly or 

 in clusters fastened to the support by an abundance of transparent gela- 

 tinous material, as a rule, just above the surface of the water on pebbles, 

 jutting stones and the like. 



Incubation. Bueno says the egg stage lasts two or three weeks or 

 less. The eggs grow darker, and at one end the red eyes, the legs, the 

 rostrum, etc., of the nymph are visible through the shell. 



Number of Instars. Bueno describes five instars, each one requiring 

 from 2 to 10 days, the last stage being the longest. 



Molting. "In molting the skin of the head splits along the eyes, and 

 rises like a lid at the front. In the body, it splits lon^tudinally along 

 the middle line of the thorax, and down the dorsum to the third or fourth 

 abdominal segment. The rostral lancets are molted entire, including 

 their insertion in the interior of the head, as well as the tracheae." — 

 Bueno. 



The above applies to any other strider. See plate XV for figure of 

 molt of Gerris. 



Matiirity. These bugs become mature in about 5 days. 



Food Habits. The wiiter has seen them feeding upon insects dropped 

 into the water and catching Ostracods at the surface film. Bueno noted 

 them feeding upon water-fleas imprisoned in the surface film. Bueno 

 says they are always in a condition of semistarvation, and, when a living 

 fly is fed them, of course they attack it in full force. When it struggles 



