Hydrophilus

Aquatic environments including marshes, ponds, and slow-moving water bodies. British populations of H. piceus are confined to low-lying marshes. One species, Hydrophilus triangularis, has been recorded from a cattle water trough fed by a windmill pump.

Widespread across multiple continents. In Britain, rare and localized to specific marsh systems in Somerset, Lewes, Pevensey, Romney, North Kent, and Norfolk. In Greece, recorded from north-western Peloponnesus as the southernmost record for the species. The subgenus Dibolocelus shows highest diversity in Veracruz, Mexico with five species.

Flight activity occurs year-round with no month entirely without flight, but peaks in spring. This pattern documented specifically for H. piceus in Britain through moth trap records.

Larvae are carnivorous; adults are omnivorous. Adults of H. acuminatus have been observed feeding on algae and thawed blood worms. Larvae prey on pond snails and snail visceral mass.

Development includes aquatic larval and adult stages. Larvae of H. caraboides emerge from cocoons in groups; one observation recorded approximately fifty larvae from a single cocoon. Larvae possess distinctive paired lateral appendages with dense brushes of hairs on abdominal segments.

Adults detect food using smell combined with touch and/or taste; larvae rely primarily on smell. Adults do not use sight alone to locate food. Adults are capable of flight for dispersal.

H. piceus is critically endangered and legally protected in parts of its range. Conservation efforts in Britain focus on maintaining habitat connectivity within flying distance and preserving large areas of suitable breeding marshes. Genetic studies indicate substantial sub-structuring between populations, highlighting vulnerability to habitat fragmentation.

• Coleoptera
• Hydrophilidae
• aquatic beetles
• water scavenger beetles
• conservation
• flight dispersal
• ontogenetic diet shift
• chemical food detection

• BugGuide
• Wikipedia
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Bug Eric: The Grasshopper Hunt
• New records of Flaviporus hydrophilus and Phellinus portoricensis (Fungi: Polypores)
• Behaviourally mediated camouflage in the furrowed crab (Xantho Hydrophilus)
• Ontogenetic changes in foraging behaviour and habitat use by the Oregon garter snake, Thamnophis atratus hydrophilus
• Uptake, distribution and loss of Cr in the crab Xantho hydrophilus
• On the Biology and Structure of the Larvae of Hydrophilus caraboides L
• Contribution to knowledge of the distribution of the rare great silver water beetle Hydrophilus piceus (Linnaeus, 1758) (Coleoptera, Hydrophilidae) in Greece
• Giant water scavenger beetles Hydrophilus subgenus Dibolocelus (Coleoptera: Hydrophilidae) from Mexico with description of two new species
• Detection of food in immature and adult stages of water scavenger beetle, Hydrophilus acuminatus (Coleoptera: Hydrophilidae)
• Population structure and its implications for conservation of the great silver beetle Hydrophilus piceus in Britain
• Spatial Ecology of the Oregon Gartersnake, Thamnophis atratus hydrophilus, in a Free-Flowing Stream Environment
• Dynamic and temporal structure of the troglobitic beetle Speonomus hydrophilus (Coleoptera: Bathyscimae)
• First complete mitochondrial genome data of Hydrophilus bilineatus deciphered within the genus Hydrophilus.