What's a water strider?

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Common Names: water strider, water scooter, water skater

Scientific Name: Gerris remigis

Habitat: Freshwater surfaces, ranging from eddies in fast-running streams to isolated stock tanks.

Predators: Insect-eating fish

Diet: Small insects that fall onto the surface of the water.

Approximate Length of Body: 14-18 mm

Length Across Leg Span: 30 mm

Color: Brownish-Black with silvery gray waterproof pile.

Can be winged or wingless

Range: Is the most widespread semi-aquatic insect in the United States and in California; occurs throughout California, except in the deserts, up to about 2500 m (8,000 ft) elevation.

Following is a direct quote from California Insects, describing the family Gerridae:

Gerrids are elongate bugs that have long legs with the claws set well back from the tips, enabling the bugs to skate on water on little depressions in the surface film. ... Water striders move by synchronous, oarlike movements of the middle legs, which are longer thna the others. Gerrids are predacious, mainly on insects and other organisms that fall on the water, but they also catch aquatic insects that come to the surface. Adults of some species are wingless, but the degree of wing development varies greatly. Apparently this is related to dispersal and habitat stability; day length and temperature have been shown to influence development of winged forms. Generally, winglessness occurs only in species that live on permanent rivers, where flight dispersal is unnecessary. About 10 species are known in California, of which one occurs only on the Pacific Ocean, and two are restricted to the Colorado River.

Water striders are capable of floating on the surface of the water by maintaining surface tension with small hairs covering their legs. If these hairs get clogged up with oils, the water strider will lose surface tension and sink. Water striders are vulnerable to being swept downstream by fast currents, but they can usually move quite quickly against the current when they have to.

For information on where this information was found, see the Bibliography.

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