|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.
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.
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.
Cluster caterpillar occurs throughout eastern Australia.
Strawberries, banana, sweetpotato, tobacco, tomato, apple, cotton, cabbages, cauliflowers, many broadleafed weeds.
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.
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.
Natural control by a range of predators, parasitoids and disease organisms maintains populations at low levels and occasional outbreaks rarely require intervention.
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.