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Great Capricorn Beetle

Cerambyx cerdo L.

French: capricorne du chêne, grand capricorne | German: Große Eichenbock, Heldbock, Riesenbock, Spießbock | Italian: cerambicide della quercia, gran capricorno

Where it lives

The great capricorn beetle can be found in most of Europe, except in northern regions, North Africa and Asia Minor. This insect lives in old and large trees on forested hills at low altitude, mainly white oaks (pedunculated and sessile oak), but it is also found in other oaks and trees of temperate and Mediterranean forests (downy, cork and holly oak, chestnut, birch, willow, ash, elm, walnut, hazel, etc.). Usually the host trees are in open sunny areas, and are large plants that are in decline and have injuries on the trunk. These trees are rare in nature, and are more abundant in manmade environments, such as in orchards, traditional farmland and landscaped parks.

What it looks like

The great capricorn beetle is a large xylophagous insect belonging to the family of the longhorn beetles (Cerambycidae). It has an elongated body with black legs and body, except for the reddish-brown end. It measures from 5 to 11 cm and its antennae are longer than its body, 11-12 cm in length. As with all longhorn beetles, males are smaller than females. The larvae of the great capricorn beetle are white and fleshy, measuring up to 10 cm long when mature.

Life cycle

Between late spring and summer, females lay their eggs in a deadwood part of old living trees. During the first year, larvae feed on the wood under the bark. In the second year, they go deeper into the trunk, feeding for 3 to 5 years and creating large galleries. In the last year, the larvae work back towards the bark and make a chamber that opens to the outside, where they develop into nymphs and then adults. Adults remain sheltered inside the chamber during the winter, and in the warmer period they fly out and mate, remaining on the bark of the host tree. Adults live 3 to 5 weeks, feeding on the sap that appears on injuries in the bark and on mature fruits.

Did you know?

  • Adults are weak flyers and very rarely fly more than 500 m from the tree where they were born.
  • When an old tree is declining and injured, it starts to emit a different spectrum of volatile organic substances, which are detected and attract the adult beetles, and induce females to lay their eggs.
  • This species has an important ecological role in the forest, undermining the wood of dying trees, and promoting their decline and faster substitution; in this way it can maintain a balanced age structure of forest trees in both space and time.
  • Due to a lack of old forests with veteran and decaying trees, this beetle is declining in northern Europe. It is therefore protected since 1992 by a European Union Directive (Dir. 92/43/EEC) and is classified as “vulnerable” by the International Union for Conservation of Nature (IUCN).
  • On the other hand, the great capricorn beetle has a higher population density in the Mediterranean region, and in some areas is considered a pest as it can seriously damage cork and holly oak forests.

Check out the European Atlas of Forest Tree Species. It has much more information about white oaks, favoured by the Great Capricorn Beetle for nesting, and about many other tree species in Europe's forests."

Learn more about the research the European Commission does on forests and forestry.