Harpalus affinis (Schrank, 1781)
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ADEPHAGA Clairville, 1806
HARPALINI Bonelli, 1810
Harpalus Latreille, 1802
This generally common and often abundant species occurs across the entire Palaearctic region with the exception of far northern areas; it is common from lowlands to about 1500m throughout Europe and Asia Minor extending to Israel and Iran and the far east of Russia, it has also spread further afield through human trade and is now established in Japan, Australia, New Zealand, Canada and the United States. In the UK it is abundant throughout England and Wales, more sparse and scattered in Scotland north to the Highlands and generally restricted to the coast in Ireland. Adults occur year-round, typically in open and rather dry habitats such as parkland, farmland and dunes but they are also synanthropic and common in gardens and other disturbed areas, they fly readily and are quick to colonize new areas. They are occasionally active during the day and may be seen running in bright sun but they are mainly nocturnal, spending most of their time running in the open and so are easily seen by torchlight. Mating pairs will often be seen in the spring but some also mate in the autumn and so most larvae develop through the summer to give new-generation adults from August, and a smaller number will overwinter to produce spring adults. Larvae are mostly predatory, feeding on small invertebrates etc, but they also consume seeds. Adults live for at least two years, exceptionally up to four, and may reproduce several times, they mainly feed on seeds and may be swept from grasses and a range of herbaceous vegetation during the summer, both by day and night, but they will also consume live prey such as aphids and small larvae and, at least in Germany, they are known to predate eggs of the cabbage root fly (Delia radicum (L.)). Adults are readily found by general searching or pitfall trapping, during the day and overwinter they remain under logs or among litter and often congregate in small numbers under loose bark.
8.5-12mm. Black, the male generally with strong metallic reflection, usually green but varies from bronze through coppery to violet or almost red, females tend to be dull black and lack the metallic reflection, margins of pronotum and elytra, at least towards apex, reddish. Appendages pale, light brown to red. Vertex of head glabrous and shiny, clypeus and labrum dull from microsculpture which is just visible at X20, inside border of eye with a single setiferous puncture. Two basal antennal segments glabrous. Lateral and basal margins of pronotum bordered although this may be interrupted across the base, anterior angles weakly protruding and evenly rounded, posterior angles obtuse and rounded, without setae. Basal fovea broad and weakly impressed, with coarse punctures which may continue along the base to the middle and forward in front of the fovea to the disc, entire surface very finely punctured. Elytra with transverse microsculpture (X20), which is stronger in the female, and 9 well-impressed striae, finely punctured and pubescent along the outer 2 or 3 interstices, otherwise smooth and glabrous. Second stria or third interstice generally with 1-3 punctures which may be weak and need careful searching for but the one towards apex is usually obvious. (This varies and we have several specimens without dorsal punctures.) Epipleurs uncrossed. Lateral margin more strongly sinuate subapically in female. Tarsi glabrous above, first segment of hind tarsi about as long as the tibial spur (Anisodactylus). Claws smooth and not toothed at base. Pro and meso tarsi dilated in male.