Bronze beetle

Systematic position. The bronze beetle (Eucolaspis puncticollis) belongs to the order Coleoptera and the family Chrysomelidae. It is a well-known pest native to New Zealand, frequently studied due to its significant impact on various horticultural crops and native flora.

Host plants. The beetle has a wide host range, primarily affecting pome and stone fruits, such as apples, pears, peaches, and plums. It is also commonly found on grapes, various ornamental shrubs, and diverse hedge species, which allows it to thrive in both agricultural and urban environments.

Biology and life cycle. This species undergoes complete metamorphosis. Adults typically emerge from the soil in late spring and early summer. Eggs are laid in the soil near the base of the host plant. The larvae develop in the soil feeding on organic matter and small roots, after which they pupate underground, eventually emerging as new adults to continue the cycle.

Damage and pest status. Adult beetles are the primary stage causing visible damage. They create characteristic shot-hole patterns in foliage, reducing the photosynthetic capacity of the plant. Moreover, they feed on developing fruit, causing surface scarring and pits, which lowers fruit quality, compromises marketability, and can lead to secondary infections.

Control measures. Integrated Pest Management (IPM) is essential for effective control. Cultural practices, such as soil cultivation under the canopy, can disrupt larval development. Chemical control involves the application of appropriate insecticides during peak adult activity. It is crucial to monitor population levels carefully to ensure the timing of sprays aligns with the insect's emergence period.