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Pachytodes cerambyciformis (Schrank, 1781)

Speckled Longhorn Beetle







POLYPHAGA Emery, 1886

CHRYSOMELOIDEA Latreille, 1802

CERAMBYCIDAE Latreille, 1802

LEPTURINAE Latreille, 1802

LEPTURINI Latreille, 1802

Pachytodes Pic, 1891

This species is generally common throughout Europe north to the UK, Denmark and the eastern Baltic countries and east into western Russia, Caucasus and Asia Minor; in the UK it is locally common in the south of England and the west midlands, throughout Wales and more local and scarce through most of Scotland. Adults are active from May until July although in higher mountain areas they occur until the end of August, the typical habitat is deciduous woodland and wooded parkland but they fly well and will travel some distance to visit flowers and so may occur away from wooded areas, e.g. we found specimens on umbel flowers beside a busy A-road in Surrey far from any woodland, they are very active and on warm days may display a habit of hovering above flowers and moving rapidly, in the way a hoverfly might move. Mating occurs throughout the season and pairs may be seen on the leaves and flowers of various shrubs and herbaceous plants, typically umbels but also meadowsweet (Filipendula ulmaria (l.) Maxim) and others. Females oviposit in dead or decaying wood of a range of deciduous trees including alder, birch, chestnut and oak, and on the continent they have been recorded on various conifers, they usually do so low down on trunks or among fallen branches and often choose damp, recently dead trunks, especially where these have been blown over. Larvae mostly develop in exposed roots, especially where these are covered in soil and patches of moss, they produce longitudinal galleries as they feed and are capable of moving through the soil to reach other roots if their food is exhausted, they develop through to the following spring when they enter the soil and construct an earthen cocoon in which to pupate, this is usually near the surface and adjacent to the roots but in order to find the correct conditions it may be as deep as 30 cm. or more. Adults form in early spring but remain in situ until May or June and freshly emerged specimens have been observed tunnelling through the soil from even the deepest cocoons. Sampling is usually a case of searching among flowers or sweeping shrubs and low vegetation but adults are easily observed and netted in flight and might be expected anywhere there are flowers near woodland margins etc.

Pachytodes cerambyciformis 1

Pachytodes cerambyciformis 1

Pachytodes cerambyciformis 2

Pachytodes cerambyciformis 2

6.5-12.5 mm. Adults are readily recognized by the broadly-rounded shoulders and comparatively narrow, campanulate pronotum, the forebody and legs are black or dark grey and the elytra orange or yellow with various dark markings, typically two transverse bands, one before and one after the middle which may be fragmented, and across the apex, but they are very variable and more than forty variations have been (pointlessly) named, in extreme cases they are entirely yellow or black with narrow transverse yellow bands but in the UK they are generally less variable and usually vary in the extent and fragmentation of the black bands.  Entire dorsal surface with short golden-yellow pubescence, that on the elytra usually brighter in colour. Head strongly produced beyond long transverse eyes, temples short and rounded, surface very densely and coarsely punctured but for a variable smooth median longitudinal line, antennae long and slender, in the male almost reaching the elytral apex, in the female shorter. Pronotum convex and slightly transverse, broadest across strongly protruding posterior angles and narrowed to a rounded anterior margin, surface very densely punctured and with two shallow transverse depressions across the base. Elytra short, about 1.5X longer than wide, broadest across widely-rounded shoulders and narrowed in almost straight lines to separately-rounded apical margins, surface smooth and without striae although there is usually a hint of a sutural stria in the apical half, finely and diffusely punctured throughout. Legs long and slender, the basal hind tarsal segment and the terminal segment of all tarsi notably so, tarsi pseudotetramerous, the lobes of the third segments deep but narrow and the fourth segment usually obvious.

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