Itchy caterpillars

Family

Thaumetopoeidae Ochrogaster lunifer Herrich Schaffer (formerly Teara contraria). Identified by L. Radunz 3 July 1980.

Food plants

Collected by P. Whelan 5 April 1982 Berrimah Northern Territory (NT) and 19 March 1982 Howard Springs NT on Planchonia careya (F. Muell.) R. Knuth, (Cocky Apple). The same species was found in a bag shelter on Eucalyptus terminalis F. Muell. on Victoria River Downs NT (P. Whelan May 1980).

Appearance

The mature larvae are relatively large and black, with a long hairy appearance. The female moth is a relatively large pale brown moth, with a brown abdomen and a cream coloured terminal end. The forewings have two small rectangular white patches centrally on the wing.

Biology

The main food plant is the Cocky Apple. It is particularly common on this tree in the wet season across the Top End of the NT. The eggs are laid on the new leaves with a covering of scales from the tip of the moth abdomen. Young larvae feed on the top surface of the leaf and leave a skeletonised appearance. Older larvae eat the whole leaf and the leaves look extensively damaged. 

The older larvae form a silken bag in which they harbour during the day and in which shed skins and excreta accumulate. The bag increases in size and can reach the size of a basketball. On an occasion when the nest was broken open on the ground, the larvae formed a processionary column and climbed back up the tree. The larvae pupate singly in the ground near the food tree.

Medical effects

While collecting larvae, I contaminated the palm of my hand and fingers. The palm was very itchy after 10 minutes and continued to be itchy for at least two days. There were still red areas on the palm 1 cm square after two days and the area was sore as if a fine splinter was inside the skin.

The hairs and skin can be airborne after disturbance of the nest. Contact with the bag can cause extensive urticaria and intense itching for at least a number of hours, even in bags where the larvae have long gone.

Contact with the female moth and egg masses will also cause reactions.

Remedy

Avoid food trees in urban or bush settings, particularly if there is evidence of fresh skeletonising or partly eaten leaves.

Remove trees in urban sites or destroy larvae at resting stage at the base of the food trees by residual application of insecticide to the trunk or leaves of the tree and by wrapping loose bagging impregnated with insecticide at the base of the tree. Burn the area around the base of tree during the day when the caterpillars are resting.

Do not have outside fluorescent or incandescent white lights on after sundown in problem areas or when moths are active.

Do not touch the pale brown moths.

Do not sleep or sit under lights when the moths are attracted to the lights.

Wash affected clothes or skin well with soap and water.

Apply ice pack or soothing lotions such as Stingose, Calamine Lotion or papaya creme. Antihistamine medications may be required for severe or generalised reactions. Medical advice should be sought for severe reactions.

Reference

Floater, G.J.1998, ‘Tuft scales and egg protection in Ochrogaster lunifer Herrich-Schäffer (Lepidoptera:Thaumetopoeidae)’, Australian Journal of Entomology, vol. 37, pp.34–39.

Southcott R.V. Moths and butterflies in Covacevich J, Davie P, and Pearn J, (editors)1987, ‘Toxic plants and animals, A guide for Australia’ Queensland Museum.