HUNGERFORD: AQUATIC HEMIPTERA. 229 
Arctocorixa 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 writer 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 pale 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. 
Oviposition. 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 downward 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 
* Although this was identified for me as the same as the Kansas form, I am satisfied 
from careful study that the varieties are distinct species. 
g 
