Budworms

Helicoverpa species (previously known as Heliothis and commonly known as budworms) are becoming more common in all Australian growing regions. The cotton bollworm, Helicoverpa armigera, and the native budworm, Helicoverpa punctigera, are the main insect pests of many agricultural and horticultural crops in Australia. The moth larvae can cause extensive feeding damage and also create entry points for secondary pests and diseases.

Pest identification

Helicoverpa spp. larvae are cream with dark-brown heads. As they mature, the larvae will become darker and develop stripes running along their bodies. These will then develop into the identifying characteristics between species. Female moths generally have brown forewings, while males are usually cream.

Damage

Helicoverpa spp. larvae will bore into developing fruitlets, causing them to either fall or become deformed. Fruit damage usually appears as clean, isolated holes in the fruit surface, 5–10 mm deep and around 5 mm wide. These develop a russet lump or depression as the fruit matures. Larvae can also feed on the leaves and buds.

Monitoring

During spring and early summer, the undersides of damaged leaves should be carefully monitored for young caterpillars. Helicoverpa spp. damage can also occur in early autumn and around harvest, making this a good time to monitor trees.

Management

Cultural and physical: Helicoverpa spp. will lay eggs on a wide range of plants, including weeds. Managing weeds, particularly during dormancy, can help reduce the resident population.

Biological: protecting beneficials by using ‘softer’, more selective insecticides will help with biological control of Helicoverpa spp. Pathogen-based insecticides are commercially available, including Bacillus thuringiensis (Bt) and nucleopolyhedrovirus (NPV).

Chemical: budworms and other early-season caterpillars can damage fruit before spray programs for other key moth pests have started. Early spring monitoring can help determine if early-season chemical intervention is needed.