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Cluster caterpillar in fruit and vegetables

  • Larva feeding on strawberry
    Spodoptera litura feeding on strawberry fruit. Younger caterpillar stage at bottom of fruit.
  • Larva and parasitic wasp (right)
    Cluster caterpillar larva and the cocoon of the parasitic wasp, Microplitis demolitor. Right: Adult wasp.
Scientific name

Spodoptera litura

Description of adult

The adults are greyish-brown moths with silvery marbling on the forewings; 16 mm in length and about 40 mm across the outstretched wings. The hind-wings are translucent white.

Immature stages

Eggs are laid on the leaves by the night-flying moth in clusters of up to 300 and are covered with a matt of grey-brown hairs from the body of the female. Young larvae are gregarious (hence the name cluster caterpillar) and feed on the lower leaf surface, causing a window effect. The young larvae are translucent green with black heads. Older larvae are solitary and have conspicuous black triangles in a line along each side of the body. Mature larvae pupate in the soil.

Life history

The eggs hatch in 2 to 7 days and the caterpillar stage lasts 2 to 6 weeks depending on temperatures. The life cycle, egg to adult, takes about 30 days in warm weather and up to 8 weeks in cooler conditions.

Moths (3 to 4.5 cm wingspan) lay clusters of eggs on the underside of the leaf.

Young larvae of Spodoptera litura feed in groups on either the top or bottom of leaves, leaving the opposite side intact. Large larvae are solitary.

Distribution

Cluster caterpillar occurs throughout eastern Australia.

Host range

Strawberries, banana, sweetpotato, tobacco, tomato, apple, cotton, cabbages, cauliflowers, many broadleafed weeds.

Damage

Minor and infrequent.

Young larvae feed in close groups and destroy one side of the leaf leaving the opposite side intact. Damaged areas appear clear at first but quickly turn brown. When larger and more solitary larvae feed on the rolled up 'cigar leaf' a 'shot hole' effect becomes apparent when this leaf expands. On rare occasions large solitary larvae feed on fruit causing superficial scarring.

Control options

Cultural

Eliminate alternative hosts such as Ipomoea spp. Spray with an appropriate chemical. Some beneficial insects, such as the parasitic wasp Microplitis demolitor, will attack the larvae.

Biological

Natural control by a range of predators, parasitoids and disease organisms maintains populations at low levels and occasional outbreaks rarely require intervention.

Chemical

  • Strawberry plant 
    First check that the damage is serious enough to warrant spraying. You need to have more than 1 plant in 250 damaged to make it worth spraying. Where necessary, spray with an insecticide. Small outbreaks are best handled by removing infested leaves by hand.
  • Strawberry fruit
    You need to have more than 6 damaged fruit per 1000 plants to make it worth spraying. Where necessary, spray with an insecticide. Small outbreaks are best handled by removing caterpillars by hand.
  • Banana
    None required, since leaf damage is mostly cosmetic and the plant quickly compensates by producing new leaves. Fruit damage is rare and usually confined to a few bunches only.

Chemical registrations and permits

Check the Australian Pesticides and Veterinary Medicines Authority chemical database and permit database for chemicals registered or approved under permit to treat this pest on the target crop in your state or location. Always read the label. Always observe withholding periods.

Last updated 29 August 2012