Bronze beetle

Adults fly and feed on warm evenings in spring and summer, October to February.

The bronze beetle is a small native beetle that flies on warm spring and summer evenings and chews ragged shot-holes in leaves, often stripping new growth overnight. It hits roses, fruit trees, grapes and many vegetables, and the grass-grub larvae feed on roots in the lawn below.

How to identify

• Small shiny oval beetles 4 to 5mm long, brown to bronze-black
• Ragged shot-holes and scalloped edges chewed in leaves, mostly overnight
• New growth on roses, fruit trees and grapes stripped quickly
• Scalloping marks chewed into the skin of young apples
• Beetles dropping or flying off when disturbed, and gathering around lights at night

How to prevent

• Turn off outdoor lights on warm summer nights, since the beetles are drawn to them
• Cover prized young plants with fine mesh through the flight period
• Keep plants healthy so they recover quickly from leaf damage
• Encourage birds and treat lawn grass-grub to reduce the next generation

How to control organically

• Hand-pick or shake beetles into a bucket of soapy water in the evening when they feed
• Spray neem oil at dusk over affected new growth, repeating every 5 to 7 days during flights
• Use pyrethrum at dusk for a knockdown during heavy beetle nights
• Treat the lawn for grass-grub larvae from late summer to autumn to cut beetle numbers
• Accept some leaf damage on established trees, which usually recover