Dorcus parallelipipedus (Linnaeus, 1758)
Lesser Stag Beetle
POLYPHAGA Emery, 1886
SCARABAEOIDEA Latreille, 1802
LUCANINAE Latreille, 1804
CLADOGNATHINI Felsche, 1898
Dorcus MacLeay, 1819
The Lesser Stag Beetle is widely distributed east to Asia Minor and Israel. It is locally common or even abundant throughout its range but, like so many other saproxylic species, has suffered a recent decline. It is protected in several European countries. In the U.K. it occurs throughout England north to Nottinghamshire and there are a few records further north but it appears to be absent from much of western Wales and Cornwall. So far it seems to be common through most of its range. The natural habitat is woodland, wooded parkland and gardens and it is a common urban species. It occurs throughout our local Hertfordshire area and is a common sight in Watford town. Adults occur year round; in the winter within soft wood, under bark or logs or among vegetation piled around the base of trunks. In spring and summer, generally April to September, they are active both by day and night; they fly well and will come to light. Nocturnal searching will usually find them on pathways and trunks. A wide range of broadleaved hosts have been recorded including oak, lime, elder, willow, elm, beech and various fruit trees. Adults may live for several years and are sometimes found in wood together with the larvae. They feed on sap and may be attracted to the syrup or treacle used as attractants by lepidopterists. Females chew at the wood or bark forming depressions or short tunnels before laying a single pale yellow egg into the wood, this is usually done at night and is easily observed by torchlight. The larval stage lasts for at least a year and maybe for as long as three and there are three instars. Sometimes large numbers of larvae occur together in a single extensively eaten piece of wood. Pupation occurs in the summer or autumn in a chamber prepared by the larva, usually just below the bark. Adults eclose in late summer or autumn. After overwintering the adults can be attracted to sap and will feed voraciously. They are said to be strongly attracted to ginger.
20-32mm. The size and general habitus will make Dorcus unmistakable among the U.K. fauna but a brief description and a mention of some of the sexual differences seems worthwhile. Entirely black or with the elytra slightly red and
the antennal club, to a varying extent, red. In the female the entire body, including the mandibles, are strongly punctured and shiny, and the vertex of the head has two closely set tubercles. In the male the elytra are punctured and shiny whereas the head and pronotum are densely microsculptured and finely punctured, and the head lacks tubercles. The male mandibles are larger than those of the female and possess a curved horn on the upper surface. The male labrum is widely transverse and feebly emarginated whereas in the female it is small and deeply notched on the front margin. The female pronotum is broadest in the basal half while in the male it is either parallel or broadest in front of the middle. In both sexes the eyes are almost divided from the anterior margin by a canthus.
DORCUS MACLEAY, 1819
Originally a small genus of around 30 species but with the recent inclusion of the genus Serrognathus there are now about 60. The two groups were previously separated by differences in the structure of the mandibles. Most species occur in India and Southeast Asia, with only two species from the western United States and four from Europe. The two species formerly classified as Dorcus from New Zealand are now assigned to other genera. Some species are large and impressive looking and as such are attractive to collectors, especially in Japan and Europe. In Asia some of the larger species are kept as pets, being bred commercially for the purpose. Inevitably some escapees have become established outside their normal ranges.
Dorcus titanus (Boisduval, 1835) is truly impressive with males reaching 110mm or more while the females achieve only half this size. The species is available commercially on many websites and is always widely available at entomological exhibitions. Which says something? It occurs throughout eastern Asia; through China and Japan and south through Korea and Indonesia. There are 20 or so regional subspecies. The natural habitat is temperate and tropical rainforests from lowlands to mountains and the life cycle is typical of the genus. Eggs are laid on underground parts of fallen trees, especially oaks, and hatch within a month or so, larvae feed on wood for about a year and the whole cycle lasts for a year or two. Adults are active from May to August and feed on tree sap.
Of the four European species one, D. alexisi Muret & Drumont, 1999, is a very local species endemic to Cyprus, being known as The Cyprus Stag Beetle as it is the only Lucanid known to occur on the island. It is considered to be endangered (IUCN Red List) and has suffered a recent decline due to exploitation and fragmentation of its wooded habitats. The natural habitat is old deciduous woodland with abundant veteran trees, orchards, copses and river valleys. Favoured hosts include Platanus orientalis (Plane), Alnus orietalis (Oriental Alder) and Juglans regia (Walnut.) They occur mostly in marginal environments where the larvae feed on dead wood among riparian vegetation. Adults have been recorded at light. D. musimon Gene, 1836 is another IUCN Red List species from Corsica and Sardinia. D. peyronis Reich & Saucy, 1856 occurs in Eastern Europe and the Middle East.
Dorcus titanus (Boisduval, 1835)