Giant wood moth

• Adults are large, mottled light grey or brownish, with a dark blotch on the thorax. They are rarely seen.
• Females have a wingspan up to 25cm and a relatively large heavy body, up to 30g. Males are generally half the size of females.
• Larvae are large, up to 15cm long and 2–3cm wide, creamy with pink-purple stripes and a red-brown head.
• The first sign of an attack is often a pile of coarse frass (similar to sawdust) at the base of the tree stem and a hole or cover of frass on the trunk.
• Tunnel entrances can be found anywhere from the base to the crown of a tree but are more frequently observed up to 3m high.
• As the larva grows, the stem of the tree swells around the entrance hole.
• Larvae feed singly in J-shaped tunnels in both sapwood and heartwood.
• Before the moths emerge in midsummer, a large, circular exit hole (3–5cm diameter) is created above the smaller entrance hole, which is often plugged with frass.
• Empty pupal cases may protrude from exit holes during summer.

• Common along the coast from North to South East Queensland, and also in New South Wales.
• Recorded 200km inland at Theodore, Queensland.

Giant wood moths typically attack trees more than 3 years old, and prefer these species:

• Gympie messmate (Eucalyptus cloeziana)
• Dunn's white gum (E. dunnii)
• rose gum (E. grandis and hybrids)
• grey gum (E. longirostrata)
• blackbutt (E. pilularis)
• Sydney blue gum (E. saligna)
• forest red gum (E. tereticornis).

• Tunnels made by the larvae through the sapwood and heartwood reduce the quality of the timber.
• Smaller trees can snap in strong winds.
• Larger trees are not significantly weakened, although the exit hole may allow the entry of water and fungi. The holes seal within about a year.
• Yellow-tailed black cockatoos tear into stems when feeding on wood moth larvae, further damaging and weakening the tree.

• Female moths produce thousands of eggs and deposit them in crevices in the bark of living trees.
• Hatchling larvae lower themselves on silken threads and are dispersed by wind. They are believed to spend their early life feeding on roots underground, but this has not been confirmed.
• When larvae are around 25mm long, they bore into the stems or branches of eucalypts, excavating a chamber in the sapwood. The hole is then sealed with a hard plug of compacted sawdust and silk.
• Larvae feed and develop for around 2 years. Their actual food consists of the soft callus tissue which the tree produces in the cambium as it attempts to seal off the invader’s burrow.
• Adult moths emerge throughout summer, typically after heavy rainfall. This life stage is short, as adults have no mouth parts and must survive on fats gained in the larval stage.

• One species of wasp is documented as a parasitoid of E. cinereus, but this has not yet been investigated as a biocontrol agent.
• When establishing hardwood plantations, avoid using species susceptible to the giant wood moth, or avoid growing them in monocultures.
• If infestation has occurred, it may be possible to deter cockatoos by using noise or light disturbance.

• Carnegie, AJ, Lawson, SA, Smith, TE, Pegg, GS, Stone, C, McDonald, JM. 2008. Healthy hardwoods: a field guide to pests, diseases and nutritional disorders in subtropical hardwoods, Forest & Wood Products Australia, Victoria.
• Jones, DL, Elliot, WR, Jones, SR. 2015. Pests, Diseases, Ailments and Allies of Australian Plants. Reed New Holland Publishers Pty Ltd, Chatswood, NSW.
• Peters, BC, King, J, Wylie, FR. 1996. Pests of timber in Queensland. Brisbane: Queensland Forestry Research Institute.
• Thurman, JH. 2022. Beyond the pest: Life history, ecology and ethnoentomology of the giant wood moth (Endoxyla cinereus). Austral Ecology, 47:733–747, viewed 2023.