Project Start: 2024
Zoo Participation: installation of new sculptures, planting of summer oaks
The oak jewel beetle (Agrilus biguttatus) is among the most beautiful and simultaneously one of the most endangered insect species in the Czech Republic. It is a roughly 2-centimeter-long metallic shiny beetle that requires freely growing, sunlit oak trees for its survival. At the beginning of September 2024, monitoring of this rare beetle took place within the grounds of the Zlín Zoo, where it is very rarely seen in the wild. With a bit of luck, adult beetles can be spotted from the end of June to the beginning of August.
In the Czech Republic, populations of the oak jewel beetle survive in four regions of southeastern Moravia and the Třeboňsko area. Recently, the grounds of the Zlín Zoo have been added to these regions. So far, the presence of this beetle in the zoo has not been confirmed by capturing an adult individual, but its occurrence was indicated by oval exit holes. These holes resemble a horseshoe-shaped ellipse, measuring 5–7 mm in length and 4–5 mm in width. During monitoring, they were found on wooden sculptures that visitors can admire in various parts of the zoo. Some of these sculptures are carved from trunks of summer oak (Quercus robur). Besides the installed sculptures, which have proven to be ideal sites for the beetle’s development, the beetle will also use other tree crowns.
Fieldwork revealed that some sculptures are no longer actively used by the oak jewel beetle for its development, while others are used much more intensively. Already in 2022, four exit holes were accidentally discovered on one sculpture. By 2024, a total of 37 holes were counted on the same sculpture.
Dead parts of trunks, thick dying branches, or damaged trees of the aforementioned summer oak play a key role in the development of the beetle larvae. Larval development is very long and may take 2–3 years. If the wood dries out, the development can exceptionally extend up to 7 years. Besides summer oak, the beetle’s development has also been recorded on winter oak (Quercus petraea) and horse chestnut (Aesculus hippocastanum).
For the survival of the oak jewel beetle population, it is crucial to ensure an adequate supply of suitable trees necessary for its development. This means protecting and not removing old and large oak trees and securing their continuity through planting. We can further support the species by installing new sculptures carved from summer oak. These should be installed vertically so that the wood has minimal contact with the ground, reducing moisture and the associated fungal diseases.
The existing sculptures inhabited by the beetle will be regularly treated every 2–3 years with a special coating. This will preserve the sculptures while ensuring the safe development of the oak jewel beetle larvae.
We thank Mr. Daniel Rydzima for providing the photographs.
