Striped jewel beetle

The striped jewel beetle (Chalcites striatus, synonymous with Capnodis tenebrionis) is a significant wood-boring pest belonging to the Buprestidae family.

Adult beetles are robust, measuring between 25 and 30 mm in length, with a matte black coloration and distinct longitudinal grooves on their elytra.

The larvae are typical buprestid larvae: legless, creamy white, with a notably enlarged, flattened thoracic segment that helps them move within wood.

The species exhibits a long life cycle, often spanning multiple years from egg to adult emergence, which makes population monitoring a challenging task.

They are primarily heliophilic insects, meaning they are most active and visible during bright, sunny days when they congregate on the bark of host trees.

The primary hosts of this pest include stone fruit trees such as apricots, peaches, cherries, plums, and occasionally almonds and other nut trees.

Adult beetles cause damage by feeding on leaves, buds, and young shoots, though this activity is generally secondary compared to the damage caused by larvae.

Larval feeding occurs beneath the bark in the cambium and sapwood, where they create winding galleries that sever the vascular transport of the tree.

Young trees are highly susceptible and can be ring-barked by larvae, leading to rapid decline and the eventual death of the entire plant within a few seasons.

This borer damage creates an entry point for various wood-decaying fungi and bacterial pathogens, exacerbating the overall stress and mortality of the orchard.

Adults emerge from their pupal chambers in the soil or wood during late spring and early summer as temperatures consistently rise above the threshold.

The mating and egg-laying period typically spans from June through August, during which females search for suitable bark crevices near the root collar.

Newly hatched larvae migrate immediately to the inner bark and cambium, where they begin their wood-boring activity that lasts for several years.

The larval stage is the most prolonged phase, with insects overwintering inside the galleries during the colder months, protected by the tree bark.

Pupation occurs in spring within specialized chambers constructed by the mature larvae, marking the completion of the biological cycle before the next emergence.

Key indicators of an infestation include the presence of D-shaped or oval exit holes on the trunk surface, signifying the emergence of a new generation of beetles.

Fine wood dust, known as frass, often accumulates at the base of the trunk or in bark crevices as larvae bore deeper into the tree's vascular structure.

A visible decline in foliage density, yellowing of leaves during summer, and sudden branch dieback are common symptoms of internal wood damage.

Bark cracking and the exudation of gum (gummosis) around the trunk base are common reactions of stone fruit trees to larval tunneling and secondary infections.

If the bark is peeled away in infested areas, clear evidence of flattened, serpentine galleries packed with frass can be observed, confirming the presence of larvae.

Cultural control practices, such as maintaining optimal soil moisture and tree health, can significantly reduce the attractiveness of trees to egg-laying females.

Applying protective barriers or trunk whitewashing can prevent adults from laying eggs in the cracks of the bark near the root collar.

Chemical control should be timed to match the adult activity period, utilizing systemic or contact insecticides to target beetles before they deposit eggs.

Mechanical removal by hand-picking adults during the early morning hours can be an effective management tool for small-scale or organic orchards.

Sanitation is critical; trees that have been severely compromised by larval activity must be removed and destroyed to reduce the local population source.