Oak Jewel Beetle

Eurythyrea quercus

Oak Jewel Beetle is a large metallic-shiny beetle, usually between 14 and 22 mm long. It is one of our most beautiful and also most endangered beetles.

For its life, the Oak Jewel Beetle needs massive independently growing oak trees lit by the sun, but can also live in Sweet Chestnut trees. Its larvae live in dead, very hard wood of the trunk and strong branches, on spots with no bark, very often in places where the activities of Great capricorn beetle (Cerambyx cerdo) larvae caused local wood necrosis. Presence of the species can be revealed by oval fly-out holes located in areas without bark and similar to a horseshoe-shaped ellipse 5-7 mm long and 4-5 mm wide. Development takes 2-4 years and adults usually appear at the end of June. The Oak Jewel Beetle occurs in South and Central Europe, from Spain to the Caucassus. In the Czech Republic it occurs in South Moravia (Náměšťsko, Břeclavsko, Moravian Karst, Veselí nad Moravou) and also in the area of Třeboňsko.

In order for this species to survive in our country, it is necessary to ensure sufficient number of suitable trees – that means to protect old and massive oaks and secure continuity of their occurrence in the future by new planting. The beetle needs dead wood, which it can find both on dead and living trees. Therefore it is also important to protect fallen trees and impede their use as fuel wood. It is desirable to take proper care of living massive trees, for example to prolong their viability by partial trimming and lowering their center of gravity. By doing so, we can – among other things – reduce the consequences of insufficient number of younger age categories of trees, which is the reality at most localities. Planting, however, is also essential, as the new trees will replace the now life-ending trees; it is good to supplement these old trees by releasing selected trees from cover edges as well. Another measure should lie in thinning vegetation cover, especially where the beetle lives in previous coppice forests or game enclosures that are now too overgrown (Soutok, Náměšťská obora). This is also meaningful everywhere else, where younger trees made the cover so thick that it is no longer suitable for the beetle (Oslava and Chvojnice valleys). In case of small fragmented localities it is desirable to ensure their better connectivity.


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