Monolepta leaf beetles are yellow-orange beetles about 7mm long, have a dark red band across the shoulders and a red spot on each wing cover.
Found throughout northern Australia and northern New South Wales, but most commonly found in coastal regions.
If larval populations in the soil are high, the emerging beetles will swarm and may migrate into nearby trees or crops, particularly after heavy rainfall.
Plant Parts: Leaves, Flowers
Season: Spring - Late Summer
Symptoms: Adults skeletonise foliage, especially on flushes. Initial chewing shows as small patches on one side. As the damage progresses, the leaves are completely skeletonised. Swarms can invade an orchard and cause serious damage over a large area within 2-3 hours. Yikes!
Control: Monolepta are readily controlled with many pesticides used on caterpillars.
Infestations are often patchy, so consider spot-spraying where numbers are highest, and leave the rest of your trees unsprayed to conserve natural enemies.
References: Arborist Network, QLD Government, Brisbane Insects, Images: iNaturalist -Chelonajill, iNaturalist - Reiner, and the FST team.
