Lichen Moths (Arctiidae: Lithosiinae)

Introduction

Species of lichen moth are found all over the world, but most Australian species are endemic (only occur in Australia). Common species in the Sydney region include the banded lichen moth Eutane terminalis, Manulea replana, the lydia lichen moth Asura lydia, the alternating footman Tigroides alternata, and the dimunitive footman Scoliacma nana,

Identification

Lichen moth caterpillars are typically dark coloured with clumps of black setae (spiny hairs) often with tufts on the back of the larva. Adult moths have a wingspan up to 60 mm, but most species are much smaller.

Adult lichen moths can be recognised by their wing colouration, and the way they hold their wings. Many rest with the wings rolled around the abdomen rather than holding them in the shape of a roof, leading to the common name of "footman".

Adult moths often have bright orange, yellow, red, black and white wing markings. In the related sub-family Arctiinae the same colouring occurs in some species, giving those moths the common name of 'Tiger Moths'.

Habitat

The small, tufted caterpillars of the Banded Lichen Moth (Eutane terminalis) are often found crawling on house walls and ceilings in Sydney suburbs. They have been found in great numbers during and after wet weather, especially on older woodwork and roofs, where lichens tend to grow. They manage to get into houses through ventilation grilles and other holes, looking for places to spin a cocoon and pupate. The caterpillars eventually pupate, to emerge as black and orange moths that congregate in gardens.

Lichen moth species are found in areas where conditions favour the development of lichen and other encrusting algae. These habitats include everything from rainforests to alpine regions, and even deserts, where algae and lichen often form encrusting 'carpets' on the ground. Lichens are often important components of natural habitats, providing nutrients and preventing erosion, and lichen moths may provide a means of measuring environmental health.

Distribution

All regions of Australia. Rainforests in northern Queensland are the most diverse.

Seasonality

Lichen moths can be found all year round except in colder southern regions. Humid summers may be responsible for sudden population explosions of these moths.

Feeding and diet

Lichens, but other encrusting algae and moss may be eaten. Mature larvae are sometimes reared from plant samples where they have been feeding on lichens on branches, leading to incorrect food plant records.

Other behaviours and adaptations

Skin irritation (urticaria) can result from handling some lichen moth caterpillars, but this is rare compared to larvae from some other moth families such as Anthelidae and Lymantriidae.

The bright colours of the adults may warn potential predators such as birds that the moths taste bad. Lichens have many toxic chemicals, and the caterpillars which feed on them can store these chemicals as a defence mechanisms. These defensive chemicals are retained in the adult moths.

Economic impacts

Lichen moths may also be good environmental indicators of pollution. Pollutants such as acid rain and heavy metals often kill lichens, and absence, or reduced diversity of lichen moth species in affected areas may indicate that damage to the lichen community has occurred.

References

• Common, I.F.B. 1990. Moths of Australia. Melbourne University Press.
• NSW Department of Agriculture. 1976. Lichen-eating Caterpillars. Entomology Branch Insect Pest Bulletin 98.
• Hesbacher, S.,Giez, G. Embacher, K. Fiedler, W. Max, A. Trawoger, R. Turk, O.L. Lange and P. Proksch. 1995. Sequestration of lichen compounds by lichen-feeding members of the Arctiidae (Lepidoptera). Journal of Chemical Ecology 21(12): 2079-2089.
• Marriott, P. 2009. Moths of Victoria. Part 2 - Tiger moths and allies - Noctuoidea (A). 36pp. + cd rom. Entomological Society of Victoria, Melbourne.