Ground Beetles of Ireland

Ocys harpaloides

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Ocys harpaloides
© Roy Anderson
Ocys harpaloides
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(Maps updated 30th November 2009)

Ocys harpaloides Serville, 1821

Description: A 4-6mm long very dark brown ground beetle with conspicuous red thorax in the typical form. Common under bark and in litter in wet woodlands. A coastal form has less contrasting thorax and lives on exposed rocks and dunes.

World Distribution: A European Southern-temperate species (83) distributed from the British Isles southwards mostly, but not exclusively, near coasts in Europe, into the western Mediterranean with an outlying population in Greece, and on Atlantic coasts south to Macaronesia and N. Africa.

Irish Status: Common throughout Ireland in woodlands and one of the few small ground beetles to be found in this habitat. However, it is near the northern limits of its range in the British Isles, and is rarely recorded, for instance, in northern Scotland (Luff, 1998).

Ecology: Two distinct forms of the species have been found in Northern Ireland. Inland, a small variety with uniformly piceous elytra, occasionally paler along the suture, occurs in wet woodland and a range of other shaded habitats including gardens. It is found abundantly under bark on dead wood, a niche shared with few other Carabidae, particularly in cooler, highland areas. A larger form exists on coastal rocks with paler, brown to rufous elytra which are darkened only on the apex and sides. This form also exists very locally on arable soils near the coast, but not in shaded habitats. The two forms have not been observed to cohabit in our area, so reproductive isolation seems likely. Despite this, no clear morphological distinction other than size and colour of the elytra has been found. The wider distribution of these forms is presently unknown.