Water Scavenger Beetles

Pronunciation

How to pronounce Hydrophilidae: /haɪˌdrɒˈfɪlɪdiː/

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Summary

Hydrophilidae, or water scavenger beetles, are a diverse family of beetles, with around 2,835 species worldwide. Most species are aquatic, with some terrestrial variations. They play vital roles in the ecosystem as scavengers and predators, although some species can be pests in certain environments.

Physical Characteristics

1‒40 mm (exotic spp. up to 50 mm). Aquatic forms may superficially resemble Dytiscidae but can be easily distinguished by antennae. Many have keeled sterna. Adult hydrophilids have long maxillary palps, which are longer than their antennae.

Identification Tips

Adults come up for air head first; move hind legs alternately. Dytiscidae come up for air tail first and move hind legs together, like oars.

Habitat

Mostly aquatic; Some terrestrial species live in dung, compost, carrion, and other decaying organic matter. They thrive in marshy, shallow, heavily weeded aquatic environments and some inhabit fresh animal waste or humus-rich soil.

Distribution

Found worldwide; in the Americas, in high humidity areas, and typically in seasonal wetlands or lakes. Reported in every state in the United States, with Hydrophilus triangularis being widespread and the largest water beetle in the country.

Diet

Larvae are predatory, consuming small invertebrates, snails, and sometimes small fish and tadpoles. Adults feed on various live or decaying vegetation and occasionally dead animal tissue.

Life Cycle

Larvae take an average of 43 days to reach adulthood. They undergo several instars, feeding on one another, and pupate in sand or sediment for about 14 days before emerging as adults.

Reproduction

Some species exhibit complex courtship behaviors involving sounds and body postures. Reproduction occurs in water with females laying eggs in damp soil near water. Some species reproduce via parthenogenesis.

Predators

Fish, birds, predaceous insects, and turtles are primary predators. Humans have also been known to eat hydrophilid beetles.

Ecosystem Role

Hydrophilids serve as scavengers, helping in nutrient cycling and may also control mosquito larvae populations, making them important for ecosystem balance.

Economic Impact

Species of Hydrophilus are reported as pests in fish hatcheries, while others have potential as biological control agents for mosquito populations.

Evolution

Oldest known fossils from the Late Jurassic period indicative of the family.

Similar Taxa

• Dytiscidae

Tags

• Hydrophilidae
• water scavenger beetles
• aquatic insects
• Coleoptera