Green manuka beetle

Systematic position: Pyronota laeta belongs to the order Coleoptera and the family Scarabaeidae. Often referred to as the green manuka beetle, it is a native species of New Zealand known for its distinct metallic green coloration and significant impact on local vegetation.

Host plants: The beetle exhibits a polyphagous feeding habit. It is primarily associated with Leptospermum scoparium (manuka), but also infests a wide range of horticultural crops, including various fruit trees, shrubs, and ornamental plants found in residential gardens and forestry.

Biology and life cycle: The insect undergoes complete metamorphosis. Adults emerge in spring and summer, engaging in intense leaf consumption. After mating, females lay eggs in the soil, where the larvae develop, feeding on organic matter and living roots of grasses and host plants throughout their larval stages.

Damage and severity: Adult beetles cause severe foliage damage, often skeletonizing leaves and leaving only the midribs intact. Larval feeding on root systems is more cryptic but potentially fatal, causing stunted growth, wilting, and increased vulnerability to secondary infections in damaged root zones.

Control measures: Management requires a multi-faceted strategy to mitigate population outbreaks. Key approaches include:

• Deploying light traps to monitor and capture adult beetles during peak flight activity.
• Applying insecticides targeted at foliage to prevent heavy feeding damage.
• Treating the soil with biological control agents like entomopathogenic nematodes to target developing larvae.
• Maintaining healthy soil structure and plant vigor through proper fertilization and irrigation.