Poecilus versicolor (Sturm, 1824)

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ADEPHAGA Clairville, 1806

CARABIDAE Latreille, 1802

PTEROSTICHINAE Bonelli, 1810

PTEROSTICHINI Bonelli, 1810

Poecilus Bonelli, 1810

A generally common species throughout the Palaearctic region from Europe and the Caucasus to the Pacific coast of Russia and Japan; it occurs throughout Europe except for the warmer Mediterranean regions and extends north to the UK and the Arctic Circle in Fennoscandia, and is one of the few beetles to occur in Greenland. In Europe it is generally common and often abundant in most of the central countries, especially in upland and mountain areas (to more than 2000 m), and otherwise locally common throughout. The species is generally common throughout England and Wales, including all the islands, and more local and to the far north of Scotland and throughout Ireland. A mesophilic and hygrophilic species typical of grassland, arable land, heaths, moors and open woodland, often on heavy and damp soils but preferring sandy or peaty soils over poorly-draining clay, but also typical of coastal dunes and damp upland moors and bogs. Adults are present throughout the year; they overwinter in the soil, among litter or under debris and are active from March until October, peaking in abundance during May and June. Reproduction occurs in the spring after the adults have overwintered and females produce eggs from May until July, egg production then stops but feeding increases in order to build up fat reserves for a second winter. Eggs are deposited in the soil and larvae emerge after about three weeks, they spend most of their time in the soil where they predate eggs and larvae of other insects, they pass through three instars within two months or so and pupate in an underground cell, the entire cycle from egg to adult taking a little more than three months. So far as is known the species is univoltine and where conditions are favourable adults will reproduce over several years and even four-year old beetles have been found. Adults are diurnal and generally active on the surface in warm weather although they remain under debris during mild spells, and they are fully winged but rarely recorded in flight. They are easily sampled by searching suitable habitats; they usually appear in small number and sometimes alongside the closely-similar and common P. cupreus (though in general the present species is less thermophilic) and so specimens will need to be examined carefully.

Poecilus versicolor 1

Poecilus versicolor 1

Poecilus versicolor 2

Poecilus versicolor 2

Poecilus versicolor 3

Poecilus versicolor 3

10.5-12.5 mm. Body broad and glabrous and bright metallic golden-green to coppery or blue, sometimes with a mottled appearance although black specimens sometimes occur, antennae black with two basal segments pale brown, legs black. Head sparsely and very finely punctured and with two setiferous punctures beside large and convex eyes. Antennae slender with all segments elongate, the first three with a fine dorsal ridge. Pronotum transverse, widest behind the middle and narrowed to very finely denticulate posterior angles and almost rounded anterior angles, surface sparsely and very finely punctured, each side with two laterobasal fovea; the inner longer and slightly oblique, the outer short situated on the inner explanate margin, in most specimens with stronger punctures about the fovea. Elytra elongate, broadest behind the middle and evenly curved laterally, basal margin strongly bordered, striae shallowly-impressed and finely punctured, interstices more or less flat, epipleura crossed before the apex. Females have more shiny elytra than males. Legs long and slender, front tibiae strongly widened beyond the antennae-cleaning notch, hind tibiae with 5-8 strong black setae along the inner margins, the first of which may be shorter than the others (some of these may be broken, in which case it is better to count the punctures). Basal segments if hind tarsi deeply furrowed externally. Males may be recognized by their dilated front tarsi.

Similar species
Harpalus affinis 1.jpg
  • Generally smaller (9-12mm)

  • Single setiferous puncture next to each eye

  • Epypleura not crossed subapically

  • Elytral margins pubescent

Poecilus cupreus 2.jpg
  • Head punctured behind the eyes

  • Internal margin of hind tibiae with 8-11 pale setae

  • Elytral striae more strongly though usually less densely punctured