hungerford: aquatic hemiptera. 229 



i4.refocoW.ro alternata Say. 



These are medium-sized Corixids, barred with light and dark brown, 

 that are to be found in pools, ponds and quiet stretches of streams 

 throughout the country. They present a perplexing range of variation 

 in size and pattern and afford a most difficult problem in the fixation of 

 the species. The wi-iter published an account of the life-history of the 

 form common in Kansas, and presents here some notes on the variety 

 prevalent in the waters about Ithaca, N. Y.* 



Habitat. While this bug has a wide range of habitat, it is found 

 perhaps more than any other in streams. About Ithaca it was often 

 taken in Bool's Brook, while other species, taken in the upper spring-fed 

 pool and in the fresh water at its outlet, were absent from the stream 

 proper. 



Hibernation. In common with many other Corixids this species is 

 active in open water throughout the winter, the adults exhibiting con- 

 siderable activity even in waters covered by a layer of ice. 



Mating. The first mating noted in nature took place April 17, in a 

 pool by a railroad trestle. The water of this pool was still very cold. 

 Pairing takes place in the water, and lasts for various lengths of time, 

 often an hour or more, during which time the female continues to feed. 

 The male mounts the female and clasps her with his forelegs while the 

 tip of the abdomen is passed around the left side. The pegs on the 

 male palae make the embrace more secure, while the peculiar structure 

 called the strigil, upon the right side of the abdomen, without doubt 

 serves a similar purpose. This latter was considered by Handlisch as 

 an instrument for stridulation, but this is denied by other workers. 



Although mating may take place any time during the day, it has 

 most frequently been observed toward evening. 



Ovipositian. The first eggs were taken April 19. There were 59 of 

 them laid upon the sides of the aquarium during the night by five 

 females. This is a little earlier than they were found in nature. In 

 nature the eggs are attached singly to any available support in the 

 water. They have been found on the stems and leaves of various water 

 plants, upon sticks and boards, upon the stones, and even on the shells 

 of living snails. 



Incubation. The duration of incubation of the eggs depends some- 

 what upon the temperature of the water. Those laid earliest in the 

 spring began hatching May 2, after a period of two weeks. In warmer 

 weather the time may be reduced by half. 



Hatching. The process of hatching with the Corixids is different from 

 that observed in the case of other water bugs. The egg shell breaks 

 about the base of the micropylar peg and then splits into six or seven 

 sections, each one of which curls outward and dowmward as the opening 

 is enlarged. The writer has often had the eggs under observation at 

 time of hatching. First the top of the egg bulges slightly, then there 

 is a sudden giving away and the nipple-like tip of the egg pops loose 



* Altliongh this was identified for me as the same as the Kansas form. I am sati.sfied 

 from careful stndy that the varieties are distinct species. 



