Forest Pests: Insects, Diseases & Other Damage Agents

Csóka, György and Kovács, Tibor (1999): Xilofág rovarok - Xylophagous insects. Hungarian Forest Research Institute. Erdészeti Turományos Intézet, Agroinform Kiadó, Budapest, 189 pp.

The highest species richness of jewel beetles is found in tropical regions. The 120 species recorded from Hungary represent less than 1 % of the total number of species known world-wide. As their English name suggests, these are usually beautifully coloured, shiny beetles. Some of the particularly nice tropical species are used in making jewellery. In this family sexual dimorphism is not characteristic, but can be found in a few examples (Anthaxia hungarica for example). The adult body is hard, most frequently elongated, and flattened, cylindrical or triangular in cross section. The body usually gets narrow toward the rear. A characteristic feature for the whole family that the prothorax is strongly connected to the mid-thorax. The size of species occurring in Hungary ranges from 2 mm to 32 mm.

Most species are xylophagous, living in or under the bark or in the heartwood of woody plants. They most frequently attack trees that are water-stressed. Larval development requires 1-3 years. These species can be very difficult to rear due to their habit of developing in living branches.

The larvae are either white or yellow, legless and blind. Their antennae are three-segmented, the lower labial palps are absent - these last two features distinguish them from the larvae of longhorn beetles. Jewel beetle larvae can be divided into two distinct groups. In the first group the body is flattened, the 1st thoracic segment is disc-like and widened, the 2nd and 3rd segments are intermediate in form between the first and the thin abdominal segments. The last abdominal segment is simply blunt. In the second group the body is more or less cylindrical. The 1st thoracic segment is less flattened and widened. The cross-section of the other segments is nearly circular, and two strongly chitinized and pointed appendages can be found on the last abdominal segment.

Their tunnels - except of the "ringbarking" species - are made in the heartwood or under the bark and are similar to those made by longhorn larvae. In the case of jewel beetle larvae the tunnels in the heartwood are more flattened in cross-section. Jewel beetle tunnels under the bark are relatively wide and flat. They pupate either in the bark or in the heartwood. The emergence hole is asymmetrically elliptical, with a flatter upper half. Occasionally it can be a blunt triangle with one angle pointing downwards, or rarely circular. The adults are fast flying, favouring the sunlight and warm temperatures. They can be found resting on flowers, their foodplants or on wood piles.

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