Prosternon tessellatum (Linnaeus, 1758)
POLYPHAGA Emery, 1886
ELATEROIDEA Leach, 1815
DENTICOLLINAE Stein & Weise, 1877
CTENICERINI Fleutiaux, 1936
Prosternon Latreille, 1834
This is a widespread and generally common Palaearctic, Asian and northern Nearctic species which sometimes occurs in large numbers in central European pine and oak forests. In the U.K. it is locally common through England north to Cumberland although records are sparser in the West Country and the northeast. In Scotland there are a few records from around the Cairngorms. The typical habitat is open lowland situations, often close to rivers or other marginal habitats, and scrubland. Adults appear from April or May and can be swept from a range of low vegetation; locally they are often seen on thistle and umbel flowers and, more especially, on Cytissus foliage. On the continent it appears to be more closely associated with wooded areas and there is thought to be an association with alder. In warm weather they may be seen high up on grass stems or fence posts etc. and we have found them in numbers by sweeping grass etc. in the evening and at night. Eggs are laid among turf or in the soil around stems and the larvae develop in the soil feeding roots and other insects; they take two years to complete their development and pupation occurs in the summer. Adults eclose in late summer or autumn and remain underground in their pupal cells until the following spring. Although they are not noted as a pest species they are often found among nursery stock or in agricultural situations. The adults are strong fliers and generally do so in the evening.
9-11mm. Distinctive among the U.K. fauna due to the symmetrical patterns produced by dense creamy-yellow pubescence which almost covers the dorsal surface, in places this runs obliquely and sometimes perpendicular to the elytral suture. The pronotum and elytra are separately rounded so giving a broadly constricted appearance, the dorsal surface is uniformly brown to black and the ventral surface black. Head transverse, the frons steeply angled in front of the convex and very prominent eyes. Antennae black; the basal segment large and curved, segments 7-10 serrate. Pronotum transverse and broadest in front of the middle, the surface finely and densely punctured. The
Prosternon tessellatum 1
Prosternon tessellatum 2
Prosternon tessellatum 3
lateral margins are sinuate; the hind angles are produced posteriorly beyond the basal margin and have a fine ridge along the dorsal surface. Scutellum prominent and usually covered with pale scales. Elytra rounded and broadest behind the middle; the striae well-impressed and punctured to the apex and the interstices are densely and finely punctured. The lateral margins are explanate from below the shoulders to the apex. The legs are long and slender, mostly pale or with the tarsi sometimes darker. Tarsi 5.5.5 with all the segments obvious and not noticeably lobed, the claw segment is elongate and slender.