Saucer bug
Naucoris cimicoides
The saucer bug is a broadly oval, olive-brown aquatic bug with a strongly flattened body. It is an excellent swimmer, using its hairy hind legs as oars for propulsion. The species is known for its painful bite, which it uses for defense or to subdue prey.
Details
Identification
Oval, flat body; powerful raptorial front legs; oar-like hind legs; head wider than long.
Social behavior
Solitary; exhibits cannibalistic tendencies at high population densities.
Diet
Feeds on various aquatic insects, larvae, small crustaceans, and occasionally tadpoles.
Hunting strategy
Ambush predator that grabs prey with raptorial front legs and sucks them dry with its rostrum.
Spawning substrate
Aquatic plants (eggs are inserted into the tissue of stems).
Overwintering
Overwintering as an adult (imago) in the bottom mud of the water body.
Ecology
Ecological role
Important predator in aquatic ecosystems for the regulation of insect populations.
Natural predators
Larger fish, water birds, and predatory beetle larvae.
Competitor species
Backswimmers, great diving beetles.
Ecosystem service
Natural pest control by consuming mosquito larvae.
Threats
Loss of small water bodies, pesticide pollution, eutrophication.
Scientific profile
Profile
Distinguishing features
Broadly oval, strongly flattened body shape. The forelegs are modified into powerful raptorial legs with greatly thickened femora. The hind legs function as swimming legs and are equipped with dense fringes of swimming hairs. The short, strong rostrum can pierce human skin, causing a painful bite ('water bee').
Role in food web
Important predator in the benthic and phytal zones of standing waters; regulates populations of mosquito larvae and other invertebrates.
Protection & threats
Main threats
Loss of small water bodies due to infilling or drainage, intensive mechanical vegetation removal in ditches, heavy eutrophication, and pesticide input from agriculture.
Population trend
stable (widely distributed and common in Central Europe)
Conservation measures
Preservation and creation of small water bodies, promotion of site-specific aquatic flora, avoidance of radical vegetation removal, and establishment of buffer zones to reduce nutrient and pollutant inputs.