Cup moths

Black slug cup moth (D. casta)

• Adult moths are brown and heavily built, with marbled forewings and a 2–5cm wingspan.
• Mature larvae (caterpillars):
  • are 20–35mm long
  • are black with a yellow-white 'skirt' and white, raised dots on their back
  • have 4 clusters of stinging spines at the front of the body.
• Young caterpillars cluster together; older larvae feed singly or in small groups.

Mottled cup moth (D. vulnerans)

• Adult moths are brown and heavily built, with marbled forewings and a 2–5cm wingspan.
• Mature larvae (caterpillars):
  • are 20–35mm long and saddle shaped with a yellowish 'skirt'
  • have 4 bunches of spines at each end, which are raised when the insect is disturbed and cause painful, sharp stings
  • vary from light green to pink with yellowish markings when young to green, grey, red and brown with yellow markings when older.
• Larvae tend to feed alone.

Four-spotted cup moth (D. quadriguttata)

• Adult moths are brown and heavily built, with marbled forewings, a line of black spots on the forewings and a 2–5cm wingspan.
• Larvae (caterpillars) are similar to those of D. vulnerans but are red with 4 pairs of black spots at each end of the body.

• Wide distribution in Australia, ranging from subtropical to temperate zones

Cup moth larvae have a wide host range, including:

• spotted gum (Corymbia citriodora subspecies variegata and C. maculata)
• Gympie messmate (Eucalyptus cloeziana)
• rose gum (E. grandis)
• blackbutt (E. pilularis)
• Sydney blue gum (E. saligna)
• southern blue gum (E. globulus)
• brush box (Lophostemon confertus).

• Young caterpillars skeletonise leaves.
• Older larvae feed alone or in groups of less than 5 per leaf and consume the whole leaf.
• They can cause extensive defoliation, but this is usually restricted to a few trees in a plantation.

• Eggs are laid in crowded groupings.
• A caterpillar feeds on host tree leaves before building an egg-shaped cocoon, where it pupates.
• A circular lid is cut in the cocoon and the adult moth emerges to recommence the life cycle.
• Usually 2 generations are produced annually.
• Outbreaks appear in cycles with large numbers occurring cyclically.

• Control is not usually necessary. Cup moths are susceptible to viral infections that cause internal organ liquefication. It is likely that outbreaks of cup moths are episodic (rather than constant) because of these infections.
• Avoid contact with the stinging spines of the caterpillars.

• 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.