Sphaeroderma testaceum (Fabricius, 1775)


A generally common species throughout England and Wales although there are far fewer records for the west country, east Somerset and Wiltshire, Wales in general and northwest England. There are a few records from southern Scotland (Cox, 2007). They occur throughout our area wherever the foodplants, various species of thistle and occasionally common Knapweed (Centaurea nigra), are abundant irrespective of habitat. We have recorded them from parks, gardens, roadside verges, woodland and wasteland. During late summer adults may be found far from the foodplants. Local areas of particular abundance, where the adults will invariably be found by general sweeping through the summer, include Common moor, the western end of Cassiobury park and the Colne flood catchment along Radlett road. Despite this local abundance it must be said that during 2007 they were much less frequent than usual and during the very wet spring and summer of 2008 we found very few specimens. Adults occur only occasionally during April and May and in our experience they do not become common until June and July and then remain so until September or October. The species normally overwinter as third instar larvae but also sometimes as adults among grass tussocks (Cox, 2007). Pupation occurs in the spring and new generation adults from May. Both larvae and adults feed on leaves.

With a little experience adults are distinctive in the field with a X10 lens. S.rubidium (Graells), with which the present species is often found, is closely similar (see ID AIDS) and Neocrepidodera spp. are similarly coloured.

3.5-4.0mm.(Joy), 2.5-4.5mm (Bienkowsky). Broad oval and entirely testaceous. Head shiny with very fine puncturation, just visible at X20. Eyes prominent and touching pronotum in normal setting. Frontal tubercles deeply bordered. Antennae separated by about the length of the first segment, filiform with all segments elongate, terminal segment angled on outer side. Pronotum densely punctured, coarsely so towards base becoming finer anteriorly. Very convex so that at least some of the fine lateral border is obscured from above, front angles prominent and produced forward so distinct from above; to appreciate these features tilt the specimen back so that the pronotum is viewed perpendicular to disc. Fine lateral border sometimes continued a short distance onto hind margin. Surface without impressed line or fovea. Head and pronotum slightly less shining in female, elytra distinctly so. Elytra convex, finely and randomly punctured although there is a tendency towards forming rows on the disc. Lateral margin strongly sinuate and bordered, with a row of fine punctures joining inside margin of border, inside this with a smooth, unpunctured (at least from base to middle) area parallel to border. Legs with fine, golden pubescence. Hind femora enlarged for jumping. Hind tarsi inserted at apex of tibiae. First segment of all tarsi dilated in male; sides subparallel from basal third to apex, in female these are elongate triangular, gradually thickened from base to apex. Fourth segment of all tarsi broadly lobed in both sexes, terminal segment elongate with two strongly curved and appendiculate claws.

Description from 4 Watford specimens at X20

See ID AIDS for a comparison of S.rubidum and S.testaceum