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Number 14
Revised June 1993
By Charlma Phillips, Principal Forest Health Scientist

Cup moths belong to a small group of moths that have unusual slug-like caterpillars which are often beautifully marked and coloured. They derive their name from the cup shaped cocoons made by the caterpillars when they pupate.

There are several different species of Cup Moth which feed on eucalypts and other native plants. Their caterpillars differ in colour, pattern and size but they all have the characteristic slug-like appearance with clusters of spines on their bodies. The spines can inflict a sharp and painful sting, rather like a nettle and the caterpillars are often known as 'stingers'. The stings may cause local inflammation if they touch bare skin but this soon disappears if not aggravated by scratching.

 
Cup Moth caterpillar - spines retracted

 
Cup Moth caterpillar - spines erect

Cup Moths are forest insects and at times have been responsible for severe damage to eucalypts in New South Wales and Victoria. Sometimes they also become pests on garden trees, especially fruit trees such as apricots, apples and cherries.
Two of the more common species found on eucalypts are the Mottled Cup Moth, Doratifera vulnerans and the Painted Cup Moth, Limacodes longerans.

Description

Eggs: Cup Moth eggs are flat and yellow in colour and are covered by hairs from the body of the female moth. They are laid in batches on the leaf surface and resemble a light brown furry mass, 5-10 mm in diameter.

Caterpillars: the caterpillars are flat, fleshy, slug like creatures. They do not have legs like other caterpillars, but glide over the leaf surface like a snail or slug. They are usually brightly coloured, green with red, blue, brown or yellow markings. There are fleshy, saw toothy protuberances resembling legs along each side of the body and rosettes of cactus-like spines on top of the body - some species have 4 sets of these rosettes at either end. The spines are retractable in some species and are erected when the caterpillar is disturbed. The head is well concealed under the body. Fully grown caterpillars range form 25-40mm in length depending on the species.

Cocoons (Pictured above): These are greyish brown and oval or cup shaped with a distinct circular lid and are usually attached to twigs or on debris on the ground.

Adults (Pictured above): The adult moths are stout bodied and thickly covered with fine light brown hairs. The forewings of some species are mottled chocolate brown with a white fringe on the hind margin. The hindwings are pale brown and also fringed. Other species have brown or reddish-brown forewings with paler hindwings and one species has transparent wings with brown margins. Male and female moths are similar in appearance but female moths are larger and male moths have toothed antennae.

Life History

There are usually two generations per year, one in late winter/spring and the other in summer/autumn. Adults emerge in late winter and in summer, mate and lay eggs. The caterpillars are found in spring and autumn. Mature caterpillars build oval or cup-shaped cocoons in which they pupate. These are attached to twigs or debris or the ground surface. The empty cocoons can be found long after the moths have hatched. Cup Moths of the second generation overwinter in the pupal stage.

Habits

Adult Cup Moths are mainly active at night and are rarely seen in the daytime. The caterpillars are gregarious when young, becoming solitary as they mature. Young caterpillars feed by skeletonising the leaves while older caterpillars eat the whole leaf, often leaving only the midrib.

Damage

It is the caterpillar (larval) stage that causes the damage. Many leaves are completely or partially eaten and many more are cut off and fall to the ground. Caterpillars are usually present in small numbers but sporadic outbreaks may cause severe damage with trees completely defoliated over a large area. However, unless attacks occur over 3-4 successive years the trees usually recover.
The Mottled Cup Moth has been responsible for the defoliation of thousands of hectares of Eucalyptus camaldulensis (River Red Gum).

Control

Natural control

Cup Moth caterpillars are very susceptible to viral diseases and sometimes entire populations are killed. In fact viral disease is the most common natural control of Cup Moth caterpillars. Outbreaks of disease usually occur when weather conditions are warm and humid and when there is overcrowding and shortage of food. Affected caterpillars stop feeding and the body swells. The body contents liquify and the skin eventually splits and releases the contents over the leaves. Other caterpillars that come in contact with this material also become infected.

Parasites and predators include wasps (several species), a biting midge, flies and occasionally, birds.

Chemical control

Because virus diseases are so common, chemical control is rarely necessary. However in situations where spraying is warranted, the recommended chemicals are maldison or carbaryl + a wetting agent. Dipel, which is a bacterial suspension of Bacillus thurigiensis, may also be used. This is a particularly safe spray as it is specific to caterpillars. Spraying with Dipel is best carried out on cloudy days or late in the afternoon as it is rapidly broken down in sunlight.

Summary

When to look:  Spring, summer and autumn

Where to look:  Look on the leaves for caterpillars.
Look on twigs, bark and debris on the ground for cocoons.

What to look for:  Look for brightly coloured slug-like caterpillars with cactus-like spines in rosettes on the body and saw-tooth projections along each side.
Look for oval or cup-shaped cocoons with or without a raised lid (if lid is raised, moth has hatched).

For further information contact PIRSA Forestry

Disclaimer: While this publication may be of assistance to you, the government of South Australia and its officers do not guarantee that it is without flaw of any kind or is wholly appropriate for your particular purpose. The Government therefore disclaims all liability for any error, loss or other consequence that may arise from you relying on any information in this publication.