Athous haemorrhoidalis

Adults measure 10–15 mm in length with a slender build. The head and thorax are black, while the elytra are brown with strong ribbing. Antennae are straight and extend to the back of the pronotum. The pronotum is distinctly dimpled across its surface and covered with greyish-brown hairs. Legs are paler brown than the elytra. Sexual dimorphism is evident: males are smaller than females, and the lateral margin of the male pronotum is less wavy than the female's. The body is covered with greyish-brown pubescence throughout.

Found primarily in forests, including broad-leaved (oak and beech) and coniferous (Scots pine) types. Also occurs in wetland habitats such as fens and peatlands. Predominantly a lowland species, entirely absent above 600 m elevation, with decreasing abundance from sea level to 500 m. In agricultural settings, larvae inhabit soil of cereal fields, orchards, and potato crops.

Widespread across Europe and Asia. Throughout the British Isles. Records include Belgium and São Miguel (Azores). Not established in North America; previous reports from British Columbia were based on misidentified specimens.

Adults are most active in July in Europe, contrasting with many other click beetle species that peak in spring. Adults emerge from soil in August, with peak emergence in late August. Larval development spans multiple years in soil.

Adults feed on pollen of flowers, including those of Pinus sylvestris (Scots pine), Rumex (dock), and Plantago (plantain). Larvae feed on roots of plants, primarily grasses in the family Poaceae, and have been observed preying on winter moth (Operophtera brumata) larvae.

Larval stage lasts 3-4 years, with larvae inhabiting soil and feeding on roots. Pupation occurs from late July to early August. Adults emerge from soil in August, with peak emergence in late August. Eggs are laid in autumn in soil among roots of host plants. Adults are relatively short-lived compared to the extended larval development period.

When disturbed, adults can flick themselves up to 245 mm into the air at takeoff speeds reaching 2.27 m/s, producing a loud clicking noise. This mechanism also allows self-righting if the beetle lands on its back. Adults climb vegetation to access foliage and flowers. Larvae move vertically within the soil profile in response to temperature and moisture conditions.

Adults serve as pollinators, specifically documented as pollinators of the frog orchid (Coeloglossum viride). Larvae function as agricultural pests through root-feeding damage. The species is an important prey item for birds, particularly tits and the collared flycatcher (Ficedula albicollis).

Larvae are recognized as damaging agricultural pests, causing wireworm damage to cereal crops, orchards, and potato cultivation. The species has been studied in agricultural entomology contexts for its life history and pest management implications. No other significant human interactions documented.

• Athous vittatusSimilar phenology with both species most active in July, though A. vittatus may be distinguished by different elytral patterning and pronotal morphology.
• Other click beetle species (Elateridae)Many elaterid species share the clicking/jumping mechanism; A. haemorrhoidalis is distinguished by its specific size range, coloration pattern (black head/thorax with brown elytra), and pronotal dimpling.

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• The invasion that wasn’t | Beetles In The Bush
• The “black bringer of light” | Beetles In The Bush
• Gardening for Solitary Bees - Buglife Blog - Buglife
• ON THE LIFE HISTORY OF “WIRE WORMS” OF THE GENUS AGRIOTES, ESCH., WITH SOME NOTES ON THAT OF ATHOUS HAEMORRHOIDALIS, F.1
• ON THE LIFE HISTORY OF “WIREWORMS” OF THE GENUS AGRIOTES, ESCH., WITH SOME NOTES ON THAT OF ATHOUS HAEMORRHOIDALIS, F.1
• ON THE LIFE HISTORY OF “WIRE WORMS” OF THE GENUS AGRIOTES, ESCH., WITH SOME NOTES ON THAT OF ATHOUS HAEMORRHOIDALIS, F.: PART I