Fool’s gold beetle

Appearance

Eggs are laid in packets, about 3 mm long, on the underside of Morning glory leaves. The larvae hatch from the eggs after 10-12 days and start feeding on the leaves, leaving small puncture marks where they have eaten. Tortoise beetle larvae are distinguished by the fork-like process on the end of the abdomen.

Final instar larva. Larvae pass through 5 instars – in other words they pass through five stages, moulting (shedding) their old skin at the end of each instar. The final (5th) moult takes them into the pupal stage. Unlike most insects but common in tortoise beetles, Fool’s gold beetles do not discard the shed skins from moults but instead pile them up into a tail on the tip of the abdomen together with some of their excreta. Larvae wave this tail around when disturbed so possibly it is used for warding off predators and parasitoids. Once the larva grows big enough it stops just eating the surface of the leaf and instead chews away at the whole leaf margin.

The final instar larva attaches itself to the underside of a leaf by digging the claws of its legs into the leaf tissue and moults into a flattened pupa. The adult beetle is formed within this pupa and eventually emerges.

Naming

Synonyms:
Cassida quadriremis Gyllenhal in Schönherr, 1808
Aspidomorpha quadriremis Lucas, 1849
Aspidomorpha tecta Boheman, 1854
Aspidomorpha silacea Boheman, 1854

Distribution

Namibia, South Africa, Zimbabwe.

Food

Host plant: Convolvulaceae: Ipomoea ficifolia = I. holosericea (Muir and Sharp, 1904); Hewittia sublobata, Barbatus edulis (Borowiec, 1997 b).

Predators

A parasitic wasp of the family Chalcididae (probably Brachymeria sp.) parasitises the pupal stage by laying an egg in the pupa which hatches into a grub-like larva that feeds on the contents of the pupa, passes into its own pupal stage inside the remains of the beetle pupa and then hatches into an adult which exits the beetle pupa by boring a neat round hole in the dorsal surface.