Larvae and adults occur in slow-moving streams and among rooted plants of lentic habitats; both life stages are piercing predators. Adults are efficient swimmers and divers.
Southeast: 9.1 and higher
Midwest: 5 and higher
Mid-Atlantic: 5 and higher
Piercer / Predator
Widespread (east of the Rocky Mtns.)
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Order: Adults with hardened forewings (elytra) covering the hind wings.
Family: Ventrally, pronotum with conspicuous curved lines near each lateral margin (notopleural sutures). Metasternum without transverse sutures. Elytra covering entire abdomen or exposing only part of 1 tergite. Hind coxae each with median portion extending in posterior direction, dividing abdominal segment 1 into lateral sclerites, but not expanding into broad plates. Without large spur on end of each front tibia. Dyticidae without broad wedge-like hind coxal plate. Scutellum usually visible; if hidden, then front and middle tarsi apparently 4-segmented and hind tarsi each with 1 claw. Hind tarsi and usually tibiae flattened, streamlined, and bearing long, stiff swimming bristles. Body usually 3–25 mm long.
Genus: Smaller beetles 3.5-5.0 mm long. Elytra with longitudinal striae. Metacoxal lines strongly convergent and almost contacting medial line anterior of metacoxal lobes, then diverging anteriorly. Metafemora lacking groups of setae at posteroapical angles.