Cryptocephalus pusillus Fabricius, 1777
Suborder:
Superfamily:
Family:
Subfamily:
Tribe:
Genus:
POLYPHAGA Emery, 1886
CHRYSOMELOIDEA Latreille, 1802
CRYPTOCEPHALINAE Gyllenhal, 1813
CRYPTOCEPHALINI Gyllenhal, 1813
Cryptocephalus Geoffroy, 1762
This widespread Palaearctic species occurs throughout Europe from Portugal to Greece in the south and to the UK and some of the southern provinces of Fennoscandia to the north; it is present across North Africa and the Near East and extends through Asia into the far east of Russia. In the UK it is common throughout England and Wales north to Lancashire, though much more local and scarce in the West Country, very local and rare further north into southwest Scotland, and there are a very few records from the Scottish Highlands and Northern Ireland, through much of this range it is by far our most common arboreal member of the genus despite having suffered a general decline in recent decades. Typical habitats are deciduous and mixed woodland and wooded parkland but they may also occur on trees in gardens and hedgerows and on individual trees on heaths and moorland etc., adults occur on a wide range of trees but are probably most common on birch, Betula pendula Roth., oak, Quercus spp, willows, Salix spp, and poplars, Populus sp. Adults are active from May until September and earlier specimens sometimes occur, they mate after a period of feeding and females oviposit during May and June, although this is likely to extend over a much longer season as all larval stages have been recorded overwintering, eggs are laid on leaves and covered with a mixture of faeces and other secretions and plant debris which will protect them from predation. This protective mixture soon dries and forms a hard scaly coating which is retained by the larva after hatching, they add to this by mixing a secretion from anal glands with leaf fragments and forming a protective case which they will carry and retain until the adult beetle hatches. Larvae develop on wilted leaves and fallen catkins, mostly of birch and hazel but also other species, they feed through the summer and autumn and enter a diapause to overwinter within the protective case, and they resume feeding for a short while in the spring when fully-developed fourth instar larvae pupate. Larvae have been recorded from leaf-litter through the winter and it is likely they continue feeding among fallen leaves in the spring but they ascend trees to pupate; after climbing up to low branches to find a suitable pupation site they seal the entrance to the larval case and pupate within. Adults leave the larval case by gnawing a hole opposite the original larval entrance, they begin to emerge in May or June and populations peak from July until August. Adults are easily sampled by sweeping or beating suitable foliage, especially on saplings and young trees and we have sampled then from flowering hawthorn on several occasions, they often occur in numbers and there will usually be a range of colour variations, they also fly and occur at flight interception traps.
2.5-3.2mm. Broadly-oval, convex and rather parallel-sided, the head largely hidden from above, with robust legs and slender filiform antennae, the colour varies widely and several varieties have been named; in general females are plain with orange head and pronotum and paler elytra with a darkened suture and sometimes dark markings about the shoulders, males are very variable, they may resemble plain females or may have darker red head and pronotum and darkened elytra, this may be (rarely) entirey black with only the lateral and apical margins narrowly yellow, or more typically bicoloured with the apical half dark or maculate and the anterior half with various darker markings towards the base, but both sexes vary greatly and a more or less continuous series from pale to dark can soon be found. The legs are usually entirely pale orange but the femora and tarsi may be partly or entirely darkened. Head hypognathous and substantially retracted into the prothorax, vertex convex, shiny and very finely punctured, eyes large, transverse and almost continuous with the margin, antennae dark with four basal segments and usually the base of the fifth pale. Pronotum transverse, broadest across acute and slightly projecting posterior angles and narrowed to a rounded anterior margin, surface smoothly convex and very finely punctured, basal margin strongly bisinuate. Elytra broadest about the middle, with curved basal margins, sinuate laterally and separately curved apically, each with strongly punctured striae which become weaker laterally and fade beyond the middle, interstices smooth and very finely punctured. Legs long and robust, especially the front pair, femora substantially visible in normal setting, tibiae smooth and tarsi pseudotetramerous, the fourth segment strongly bilobed. Males may be distinguished by the dilated basal segment of the front tarsi. Very similar to C. fulvus (Goeze, 1777), with which pale specimens may be confused.