Family: Gyrinidae, Whirligig Beetles view all from this family

Description 3/8-5/8" (9-15 mm). Broadly oval, flattened. Shiny to dull black, often with a bronzy sheen. Scutellum concealed. Elytra have 9 impressed lines.

Food Adult eats aquatic insects and insects that fall into the water. Larva preys on mites, snails, and small aquatic insects.

Life Cycle Eggs are deposited in rows or masses on submerged plants. Aquatic larvae hunt prey, crawl out of water when fully grown, and construct pupal cases of sand and debris. Adults overwinter on plants or in mud. 1 generation a year.

Habitat Surface film of ponds and slow streams.

Range Throughout North America.

Discussion Adults gather in restless swarms a few feet across. If threatened, a few may dive while the rest swim erratically away at the surface. The species within this genus can be identified only on the basis of male genitalia.