190 THE UNIVERSITY SCIENCE BULLETIN. 
Biology of Notonecta undulata Say. 
Habitat. Notonecta undulata, besides being the most widely-dis- 
tributed form, seems to be able to adapt itself to a wider range of cir- 
cumstances than most of the others. The writer has taken it in clear — 
spring-fed pools in New York and in the stagnant scum-covered waters 
of muddy ponds in Kansas. Uhler, 1876, says “it inhabits the foulest 
pools, in dirty slush and slimy ponds it revels in full enjoyment of the 
filth.” 
Barber, 1913, in a popular paper on -aquatic Hemiptera, makes a 
similar reference to its habitat. Thus it may be noted to be less sensitive 
than many others of its genus to its environment. When the small bodies 
of water recede during the prolonged period of dry weather, which we 
sometimes have in late summer in Kansas, it is among the last to take 
wing to more favorable situations, a fact which is not to be accounted 
for on the basis of weak powers of flight, for it does on occasion fly very 
well, as appears to have been noted for the European forms at an early 
date. Aldrovandus spoke of them as amphibious bees and Swammerdam, 
at the close of his discussion of the Notonect#, a name applied to them 
by Mouffet, 1634, makes the following interesting remark in regard 
to the migration of water bugs: “As all the insects hitherto enumerated 
have wings, some of them flying in the daytime and others at night, it is 
easy to conceive that they may be very speedily generated in all standing 
waters.” 
In the first warm days of spring, the writer has observed them com- 
ing by the dozens and alighting in a small road-side pool. Thus their 
range, which was restricted by the drouth of the previous fall, was again 
extended to the many favorable pools of spring and early summer. There 
are several records of Corixid migrations in this country but only one, so 
far as the writer knows, for Notonecta. In September, 1846, near the 
head waters of the Mississippi, S. G. Simpson reported a swarm of “N. 
glauca,’ which extended over 25 or 35 miles. This species, if a Noto- 
nectid at all, was doubtless the common N. undulata. 
Hibernation. The adults may be taken any time duzing the winter 
when the waters are open enough to permit collecting. They pass the 
coldest portion of the year in the mud or among the rubbish and dead 
leaves in the pool. They can even spend as long as six weeks in damp 
piles of dead sticks, so it does not necessarily follow that they perish be- 
cause pools diminish during weather when they are but sluggishly active. 
Mating. Mating takes place with the first warm days of spring, and 
as with other water insects takes place beneath the surface and lasts for 
some time. 
Oviposition. The eggs are glued to supporting vegetation, sticks, 
posts, rocks, tin cans, or even to snail shells that lie submerged. A 
very satisfactory idea of the eggs may be obtained by viewing the 
photograph on plate XXI. 
Incubation. The egg stage varies from five days to two weeks, de- 
pending upon the temperature. 
