Elater ferrugineus Linnaeus, 1758
The genus Elater includes about 50 species with a worldwide distribution; the widest diversity occurs in the Oriental region. Of the 8 Palaearctic species only 2 occur in Europe. Elater ferrugineus Linnaeus, 1758 is a widespread Western Palaearctic species occurring throughout Europe, including Scandinavia and the U.K, but it is generally rare and in all countries its occurrence is sporadic. In the U.K. there are records scattered around the Thames basin, Cambridgeshire, Suffolk and a single record from the Swansea area. However, the adults are very rarely seen and so the distribution may be much more extensive; recent pheromone trapping would suggest this to be the case. A stenotypic species, typical habitats are old deciduous forests with hollow trees, wooded parkland and meadows, and sometimes individual old and hollow trees. Adults appear from the end of June until August and are crepuscular or nocturnal, sometimes coming to light, and are occasionally active during the day. The larvae inhabit the putrescent hollows of old ash, elm, beech, willow and oaks and prey on other saproxylic insect larvae, particularly the eggs and larvae of Lucanids and other Scarabaeoidea, and will often occur in wood previously infested with such larvae. In captivity they have been reared on worms and Dorcus larvae. The life cycle takes 4-6 years depending on the food source. Pupation occurs in the spring. On the continent Elater is a specialist predator of the Lucanid Osmoderma erimita, the Lucanid sex pheromone acting as a kairomone for locating the beetles.
At 17-24mm Elater is one of our largest click beetles and, being strikingly coloured, generally unmistakable. They are sexually dimorphic; males are bright red or orange with a darker head while the females are much smaller and uniformly dark brown. The posterior margin of the pronotum and the legs are dark, almost black. Two forms occur-at least on the continent - f. occitanicus Villers, 1789 has the pronotum entirely dark brown or black while f. morio Schilsky, 1888 is entirely dark brown to black. The species is broad overall with the anterior part of the pronotum very convex, the hind angles strongly produced back and sharply keeled. The elytral striae are shallow and the interstices transversely rugose, especially towards the base. The antennae are serrate from the fourth segment, the second segment is transverse, the third quadrate. The terminal segment is distinctly constricted in the apical third.