Monoleptus or Red Shouldered Leaf Beetle Advice
The beetles are 6 mm long and yellow, with a dark red (purple) band across the shoulders and two purple spots on the ends of the wing covers. The flaccid yellowish eggs are small (less than 1 mm across) and oval. The larvae are white, slightly flattened with hard brown (sclerotised) plates at both ends, and reach 10 mm in length.
The adults are easily distinguished from other beetles by their distinctive coloration.
Throughout northern Australia
Adults feed on many types of plants. Of the summer legumes, soybeans, navy beans and mungbeans are particularly attractive hosts. Other crops include cotton, sugarcane and pasture grasses. Larvae feed underground on the roots of sugarcane and pasture grasses.
Eggs are laid in the soil surface, mainly in pastures and sugarcane. The larvae feed on grass roots and pupate in the soil. The life cycle takes about two months during summer and there are three to four generations annually. Adults usually emerge from the soil after heavy rains following a dry spell. If larval populations in the soil are high, the emerging beetles will form a swarm and may migrate into nearby crops.
Adult beetles attack leaves and flowers. High populations (e.g. 50 per square metre) will shred leaves and denude crops of flowers.
Infestations are likely after heavy rainfall.
Contact your Local TGT Representative for further advice