Lucanus cervus

Life cycle

Adults appear during late May to the beginning of August, being most active in the evenings. Females lay about 30 eggs in a piece of decaying wood deep in the soil. Stag beetle larvae, which are blind and shaped like a letter "C", feed on rotting wood in a variety of places, tree stumps, old trees and shrubs, rotting fence posts, compost heaps, and leaf mould. The larvae have a cream-coloured, soft, transparent body with six orange legs, and an orange head which is very distinct from the very sharp brown pincers. They have combs in their legs which they use for communication (stridulation) with other larvae. The larvae go through several instars (stages),^[19] taking several years to become pupae. Males use their large mandibles to fight with each other in competition for females, intending to throw their opponent off the log or branch they are on.^[20]

The work of entomologist Charlie Morgan during the late 1970s discovered that the pupae of the stag beetle live in the soil for about 3 months, then emerge in summer to awkwardly fly off to mate.^{[citation needed]} Adults suck up the liquids of nectar, fallen fruit, and tree sap. Their slow, lumbering flight, usually at dusk, makes a distinctive low-pitched buzzing sound. The males fly more readily than the females.

Lifespan

Stag beetles spend most of their life as larvae and can take from 3 to 7 years for them to pupate,^[21] but the lifespan of the adults is only a few weeks.^[22]

Daily activity, use of space and detectability

In a primary ancient forest in northern Italy, stag beetle males were less elusive than females. Males were more frequently radio-tracked in flight, females mostly underground and in the proximity of deadwood. Males were mostly observed flying at sunset, and resting or walking on standing trees during the day. The combination of air temperature and humidity determined the optimal weather conditions for male flights. Flying at sunset, mostly performed by males, significantly increased the detectability of the species. ^[23] Stag beetles are shown to be more active during the first part of their adult lives. Males were more prone to disperse than females but the home range size did not differ between the sexes. Dividing the flight season in three intervals, the most active individuals were recorded during the first and the second ones (first and second half of June).^[24]

Predators

Natural predators of L. cervus in Britain include cats, foxes, badgers, carrion crows, magpies, woodpeckers, kestrels, and false black widows; these tend to strike at the most vulnerable stage in the beetle's life cycle, when adults are seeking to mate and lay eggs.^[15] In the case of magpies, they have been observed in the field as waiting for emergence on a single site, subsequently consuming the beetle's abdomen.^[25]

In Italy, the main predator is the hooded crow (Corvus cornix).^[26]

Parasites

Mites in the order Monogynaspida (Suborder Uropodina) are phoretic (attached for the purpose of transportation) and have been observed attached to L. cervus as deutonymphs on the membrane of the joint between head and pronotum.^[27]

Protection

Lucanus cervus is listed as Near Threatened by the IUCN Red List.^[1] Although this species is widely distributed in Europe, it is in significant decline in the north and central part of its range and future trends of European forests will pose serious threats to this species, thus making the species close to qualifying for Vulnerable.^[1]

Lucanus cervus is registered in the second appendix of the Habitats Directive of the European Union from 1992, which requires that member states set aside special areas of conservation. The species is also registered in the third appendix of the Convention on the Conservation of European Wildlife and Natural Habitats (Berne convention) of 1982 and Schedule 5 of the UK's Wildlife and Countryside Act 1981.^[19]

Log pyramids

Log pyramids, also called stumperies, are vertical log piles where the logs are buried upright, providing plenty of underground rotten broadleaf wood for stag beetle larvae to feed on, as their natural food sources are in decline.^[28]