LIBRARY

296
COLLEGE ENTOMOLOGY
widest part of the body and almost as long as the abdomen; prothorax the
longest part. Wings absent, reduced, or present. Hemelytra velvety; clavus
long; corium and membrane well developed. Forelegs short, more or less rap­
Lorial. Middle and hind legs long; arising close together and distant from fore
:lair; hind femora extending far beyond tip of abdomen. Coxre widely sepa­
,:lted. Tarsi two-segmented. Claws ante-apical, rarely with arolia. Abdomen
8 D
FIG. 98. A common North American water strider. Rhagovelia obesa Uhler. A. hind tarsus;
Band C. middle tarsi; D. fore tarsus. (Redrawn from Garman. 1912.)
long and slender in the fresh-water forms or greatly reduced in the small
apterous marine Halobates.
These insects are highly specialized for a life on the surface of the water.
While they generally walk, run, or skate on the surface, they can also walk
over water plants and along the shore margins, and when excited or disturbed
they hop about in an erratic manner, falling as often upon their backs as right
side up. The arrangement of the tarsi and claws is such as to give both buoyancyand
traction on the surface of the water. These hunters glide about with
an ease and speed that are astonishing. The winged species fly at night, which
accounts for their wide and rapid dispersion to small and large bodies of water.
The marine H a/abates, which inhabit the surface of tropical and subtropical
oceans, especially areas covered with seaweeds,· have been observed hundreds
of miles from land.
The life histories appear to be relatively simple. The young hatch from the
submerged eggs and at once begin life on the surface. There may be from one
to several generations a year. In cold regions adults may hibernate under
stones, logs, and other debris around the margins of water, and in semiarid
regions they may ::estivate under similar objects about the dried ponds, awaiting
the return of the wet season.