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Orsodacne humeralis Latreille, 1804





POLYPHAGA Emery, 1886

CHRYSOMELOIDEA Latreille, 1802

ORSODACNIDAE Thomson, C.G., 1859

Orsodacne Latreille, 1802

This is a widespread but generally very local and uncommon species throughout south and central Europe from Spain to the Balkan Peninsula, Asia Minor and Iran in the south and from France to western parts of Russia in the north, it extends to the UK but is absent from the northern Baltic countries, it is also known from Morocco and various Mediterranean islands. In the UK it is very local across south east England and the West Midlands and it is thought to have declined over recent decades although, as our local experience shows, it can be common where it occurs. Adults occur from March to June, peaking in abundance during late May and early June, they may be found on a variety of trees and shrubs including birch (Betula pendula Roth) and hawthorn (Crataegus monogyna Jacq.) and locally we have found them repeatedly on aspen (Populus tremula L.). They have also been recorded from recently cut branches of cypress, adults do not feed on foliage but they are fully-winged and visit a range of flowers to consume pollen and nectar, the majority of records are from hawthorn blossom but they have been recorded from a range of flowering trees as well as clover (Trifolium L.), various thistles (Cirsium Mill. and Carduus L.) and Umbels. Little is known about the life history but mating pairs may be found on flowers through the season and eggs have been laid on leaf scales or within apical shoots on dead oak twigs under artificial conditions. The larval feeding site is unknown but they are thought to overwinter, possibly in oak buds, following a long summer aestivation as first instars have been recorded in early spring, they pupate later in the spring and adults emerge from March. Adults may be beaten from foliage and flowers but they are easily spotted on flowers and mating pairs tend to remain in situ for long periods and so are easy to find.

4.0-7.0 mm. Very distinctive in overall appearance but closely similar to our other member of the family, O. cerasi (Linnaeus, 1758), more especially so as both vary widely in colour, but the present species may be distinguished but its dense dorsal pubescence. The colour varies from completely black or dark blue to pale yellow, specimens may be extensively pale with a dark head and/or pronotum, and may have pale elytra with the sutural area darkened. Head hypognathous with prominent convex eyes and short converging temples, surface flat, finely punctured and without impressions between the eyes, antennae inserted laterally above the base of the mandibles, 11-segmented and weakly serrate. Pronotum broadest in front of the middle and narrowed to a straight basal margin, anterior margin smoothly rounded, lateral margin not bordered, surface moderately strongly but not densely punctured throughout, without sculpture. Elytra long and almost parallel-sided, with rounded shoulders and a continuous apical margin, without striae but randomly puncture throughout, the punctures about as strong as those on the pronotum but a little denser. Legs long and robust, femora without ventral teeth, tibiae widened towards truncate apical margins, all with two fine apical spurs. Tarsi pseudotetramerous, the small fourth segment partly hidden with the broad lobes of the third, claws smooth, and toothed at the base.

Orsodacne humeralis 1

Orsodacne humeralis 1

Orsodacne humeralis 2

Orsodacne humeralis 2

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