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Trinodes hirtus (Fabricius, 1781)






POLYPHAGA Emery, 1886

BOSTRICHOIDEA Latreille, 1802

DERMESTIDAE Latreille, 1804

TRINODINAE Casey, 1900

Trinodes Dejean, 1821

This very local and generally rare species occurs throughout Europe and Mediterranean North Africa extending east to the Caucasus, Asia Minor, Turkmenistan and western Russia; here it is very local and scattered with records from the south of England including London, Suffolk, the midlands and the Severn Estuary but it is difficult to find and is probably  under-recorded. The species is listed as a Grade 1 Old Forest Indicator and the typical habitat is old established broadleaf woodland with plenty of damaged and decaying trees but it also occurs in old trees in parkland and gardens and on the continent has been recorded from domestic lofts, sheds, farm buildings and mills. Adults occur from very early in the year until July or August and are active at night when they may occasionally be found wandering on the surface of dry denuded wood but they generally remain beneath loose bark or in hollows, they will also become active during the warmest weather when they bask on trunks or in flower heads in full sunlight. Both adults and larvae are associated with various subcortical spiders and for this reason may occur near dwellings where synanthropic species e.g. the house spider, Tegenaria domestica (Clerck, 1757) occur but they are not otherwise associated with domestic situations, both stages move freely on webs and it is thought that their long setae defends them from attack. Larvae occur from early summer, they feed on the remains of dead insects on webs and develop over a long period, overwintering under bark and becoming active during warm spells, they pupate over a wide period, depending on the season, and adults emerge within two or three weeks, in Poland they have been recorded as early as February. Sampling will require a great deal of searching as the adults are solitary and usually occur alone or in small numbers but larvae may be common in a small area of spider-infested bark, sometimes along with other dermestid larvae with a similar lifestyle e.g. Ctesias serra (Fabricius, 1972) or Attagenus pellio (Linnaeus, 1758), and taking extraction samples from such habitats can be productive but is also damaging. Adults have been taken from water traps placed on the ground around old trees and by sweeping flowers and foliage in similar situations.

Trinodes hirtus 1

Trinodes hirtus 1

© U.Schmidt

Trinodes hirtus 2

Trinodes hirtus 2

© Lech Borowiec

This small dermestid should be obvious from the general form and the long erect setae to the dorsal surface. Elongate-oval, convex and continuous in outline, entirely shiny dark brown to black or with the elytral margins and apex variously pale, upper surface finely and randomly punctured and with long erect and sub erect black setae. Head deflexed and mostly hidden from above, evenly convex and with a single small ocellus between large convex eves which occupy most of the lateral margin, antennae short and slender with a loose 3-segmented club; the penultimate segment transverse and almost symmetrical. Pronotum broadest at acute posterior angles and narrowed to a rounded anterior margin, basal margin strongly bisinuate, disc evenly convex to a strong sub-lateral carina in the basal half.  Elytral base strongly sinuate, following the curves of the pronotum, lateral margins evenly curved to a continuously rounded apical margin, surface finely punctured and lacking striae. Legs slender and entirely pale brown; femora unarmed and only narrowly visible from above, tibiae without distinct apical spurs. Tarsi 5-segmented and slender, without lobed segments, claws small, weakly curved and with only a very weak basal tooth.

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