The lucane owes its nickname of kite to the large and powerful mandibles wood-shaped deer which remain the prerogative of males. Zoom on the largest and most widespread of European insects.
The stag beetle and its large doe
The kite lucane (Lucanus cervus) belongs to the order of beetles, the Lucanidae family and the Scarabéidae superfamily. The nickname of large doe is attributed to the female (not to be confused with the small doe – Dorcus paralellipipedus – another Lucanid. The kite lucane presents a dimorphism very pronounced sexual: the male has mandibles hypertrophied reminiscent of the antlers of a deer and displays much larger dimensions (up to 8.5 cm long) than those of the female (from 2 to 5 cm). most tall European beetle owes its size to the quality nutritional of the wood it feeds on. This is why, depending on the regions of France, its size is classified as major, medium or minor.
What are the mandibles of the kite stag beetle used for?
Nature being well made, the powerful mandibles of the male serve as weapons of fight during jousts between rivals to access a female and mate. Jaws cannot pierce the solid shell of the opponent but they allow him to grab his legs and unbalance him while remaining at a distance. The loser being the one who will be overthrown on the back. The male also uses his mouthparts to support his partner during mating. In the female, the mandibles are smaller but can pinch more strongly. She also uses this force to sink into rotten stumps and lay his eggs.
The kite lucane, heavy and noisy
In the kite stag beetle, the head, the pronotum (upper part of the prothorax) and the six legs are black. Its bent antennae end in the form of leaves. The elytra, which serve to protect the other pair of wings, sport a dark brown to reddish brown, like its mandibles. The beetle is most easily observed from May to August, with a peak in June in wooded areas or forest paths facing south. Very active in sleep from the sun, beetles can be recognized by their heavy and noisy flight.
Habitat and food are one
The kite stag beetle is found throughout Europe, as far as southern Scandinavia. At all stages of development, the insect needstrees to find accommodation and food. In France, it is often found in the forests of Oak trees and chestnut trees but it does not shy away from other hardwoods such as elms, maples and beeches. If the beetle likes large forest areas, it does not disdain more modest woods, groves, parks and hedgerows. With pointed mandibles, females are able to incise trees to ooze the sap which it consumes and which also benefits the male. Beetles supplement their diet with a little nectar and fruit. Larvae saproxylophages consume only decaying wood.
The three lives of the kite lucane
The female lays eggs in the ground, a few inches from a sick or dead wood stump. The development of the kite lucane will then go through three steps :
- The sentence larval. Measuring up to 10 cm for a maximum weight of 30 g, the larva can live up to 6 years feeding on rotten wood;
- The sentence pupal. During the fall, after having spent several years in its nourishing tree, the larva digs a solid ovoid shell made of earth and wood in order to pupate;
- The sentence adult (imago). The nymph will transform into an adult and come out of its compartment to reproduce the following spring.
At the end of reproduction, adults survive on average a month. The male usually dies after mating while the female dies after spawning in summer.
The kite stag beetle population threatened
The predators natural larvae of the adult lucane include birds (jay, magpie, raptors, etc.) which take advantage of its slow flight to capture it while the larvae fall prey to wasps and carnivorous beetles, especially the tiger beetle. The very slow development of the beetle as well as theinterview regular forests (stumping, elimination of old trees, replacement of deciduous forests with conifers) threatens the sustainability of this insect which can no longer find enough to eat.
The kite lucane is protected
Endangered, the species is listed in Annex II of the European directive “habitats, flora and fauna” of 1992, which requires the establishment of special areas of conservation by the Member States. The kite stag beetle is also protected by the Bern Convention and listed on the European Red List of the International Union for the Conservation of Nature (IUCN). As seen previously, the beetle is saproxylophagous. As such, it is not a harmful, on the contrary, because it contributes to the cleaning of dead wood. To participate in the conservation of this species, it is enough to keep old tree trunks and stumps in our paths and gardens. The kite lucane will thus find food and shelter there.