California Department of Fish and Wildlife
Aquatic Biological Assement

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Hydrophilidae Level 1 Level 2






Key Characters (adult)

Water scavenger beetles. Many experts include Epimetopidae, Georissidae, Helophoridae and Hydrochidae as subfamilies of Hydrophilidae. Another subfamily, the Sphaeridiinae, is generally considered not aquatic. Found in nearly all freshwater habitats as well as brackish water and intertidal. Adults oval, ranging in size from 1-40 mm; antennae with the apical 3 segments forming a loose to compact club; maxillary palps may be longer than the antennae; scutellum usually distinct; tibiae may be slightly flattened, with spines (Berosus has fringe of swimming hairs).

Key Characters (larva)

Larvae with 5-segmented legs and a single claw; usually only 8 distinct abdominal segments (except for Berosus, which has 10 distinct segments and long, lateral gills); abdominal segments 8 and reduced 9th modified into spiracular atrium (except for Berosus); head well scleritized; shape and arrangement of teeth on labroclypeal margin diagnostic for generic identifications; except for scleritized pronotum and smaller scleritized plates of other nota and abdomen, body mainly membranous with transverse folds and tuberculate processes.

Tolerance 5
Distribution CA, OR, WA, NV, AZ, Baja