Common Water Strider
Gerris lacustris
The common water strider is a species of bug that moves across the water surface using surface tension. It has a slender, dark body and long middle and hind legs covered with water-repellent hairs. The species is widespread in Europe and inhabits standing and slow-moving waters. It locates its prey by detecting vibrations on the water surface and captures it using its shorter front legs.
Details
Identification
Dark brown to black upper side, light line on the edge of the pronotum, very long middle and hind legs.
Social behavior
Often found in groups, but exhibits territorial behavior and competition for prey items.
Diet
Feeds predatorily on insects that fall onto the water surface or live there.
Hunting strategy
Ambush predator that perceives surface vibrations with sensory hairs on the legs and pounces on the prey.
Spawning substrate
Underside of aquatic plants, stones, or floating objects just below the water surface.
Overwintering
Adults overwinter on land in dry riparian vegetation or moss.
Ecology
Ecological role
Important predator in the neuston; regulates populations of mosquito larvae and other small insects.
Natural predators
Fish, backswimmers, water spiders, and insectivorous birds.
Competitor species
Other water strider species of the genus Gerris as well as surface-dwelling bugs.
Ecosystem service
Biological pest control by consuming mosquito larvae.
Threats
Input of surfactants (detergents), destruction of riparian buffer strips, water pollution.
Scientific profile
Profile
Distinguishing features
Yellow longitudinal stripe on the lateral margin of the pronotum (propleura); fore femora pale with two black longitudinal stripes; pronounced wing polymorphism (macropterous, brachypterous, or apterous); genus characteristic: middle legs attached far back on the thorax.
Role in food web
Important predator of the neuston; regulates insect populations on the water surface; serves as prey for fish and larger aquatic bugs.
Protection & threats
Main threats
Water pollution by surfactants and pesticides; loss of riparian vegetation; desiccation of small water bodies due to climate change.
Population trend
Stable; widespread and common, considered one of the most adaptable water strider species in Central Europe.
Conservation measures
Protection and restoration of riparian zones; reduction of detergent and agrochemical input into water bodies.