Latridius minutus (Linnaeus, 1767)
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POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
LATRIDIINAE Erichson, 1842
Latridius Herbst, 1793
Native to the Palaearctic region and adventive in North America, this species is now Holarctic in distribution; it is widespread across North America from Alaska to Nova Scotia and south to California and Kansas, it is locally common and often abundant across Europe lowlands to the alpine region from the Mediterranean to the far north of Fennoscandia and, because of its association with stored organic matter, has been recorded sporadically across the world e.g. from Australia and South Africa. In the UK it is generally very local across England and Wales north to the Humber and only very rarely recorded further north to the Scottish border although there is also a record from the Highlands above Inverness. The species occurs in all types of decaying vegetable matter, in the wild usually among grass or manure, moss, leaf-litter, straw and hay, fungi and accumulated debris under bark or among well-decayed wood, also recorded from avian nests, anthills and old hymenopteran nests, but also in a wide range of stored products in barns, basements and damp dwellings. Adults occur year-round, both in the wild and in artificial conditions; they are generally common through the winter but increase greatly in abundance from May or June until September when numbers decrease. Breeding occurs at all times except the warmest parts of summer and females oviposit among mouldy and damp organic matter where the larvae will develop. Both adults and larvae feed on fungal spores and hyphae; the larvae are elongate and pale yellowish with a distinct head capsule and urogomphi, they feed externally and are sometimes present in large numbers among grains and cereals that have been stored without adequate drying. Adults are nocturnal and generally very inconspicuous although they become less so in dwellings where they sometimes fly, disperse in numbers and settle on walls and around windows etc. In many northern temperate regions this is the most common member of the family associated with stored products, it is also frequently found among cargoes of wheat, flour and linseed meal etc, but it causes very little economic damage as it usually attacks only materials that are already damaged by other pests and that are stored with sufficient moisture and fungal infestation. The most effective way to sample adults and larvae is by taking likely samples for extraction.
1.2-2.3 mm. Elongate with a relatively narrow forebody compared with the broadly-oval elytra, appearing glabrous but extremely finely pubescent above, entirely brown; when mature two forms occur, a dark brown form and a pale yellowish-brown form, in both cases the legs are coloured as the body but the antennae are pale. Head coarsely sculptured between prominent and coarsely-faceted eyes but without fovea or keels, not or only weakly produced in front of antennal insertions which are close to the anterior margin of the eyes. Cheeks short, labrum broadly transverse, short and weakly curved anteriorly (hence the common name). Antennae 11-segmented, with the basal segment expanded and 9-11 forming a weak and elongate club. Pronotum transverse, broadest behind produced anterior angles and smoothly narrowed to slightly obtuse posterior angles, apical margin curved forward, basal margin straight, lateral margins very finely serrate, surface roughly sculptured and densely punctured, (usually) broadly explanate and with deep basal fovea but without (distinct) keels. Prosternal process with an indistinct keel; this is usually visible only behind the coxae which are closely approximated and situated close to the basal margin. Metasternum moderately strongly and densely punctured and with numerous fine lines (can be difficult to appreciate, even with strong lighting) radiating towards the middle from distinct post meso-coxal impressions. Elytra smoothly curved from rounded shoulders that are slightly produced forward to a continuous apical margin, lateral margin narrowly explanate from the shoulders to behind the middle and very finely dentate from the base, striae strongly punctured from the base, becoming weaker from the middle, interstices roughened and often cross-strigose in the basal half, the fifth sometimes raised but not distinctly keeled. First abdominal sternite punctured and sometimes dull but never microsculptured. Legs long and slender with narrowly clavate femora and tibiae that are hardly expanded from the base and have extremely fine apical spurs. Tarsi with three simple segments in both sexes. Claws smooth and without a basal tooth. The sexes usually cannot be distinguished by external features but in males the seventh tergite is slightly concave.