Sweet Potato Tortoise Beetle

Cassida circumdata

Wing cases flared into a see-through tortoise shell

The Sweet Potato Tortoise Beetle is a small leaf beetle shaped like a miniature tortoise shell. Its wing cases (elytra) and pronotum flare into a translucent margin that hides its head and legs. Pressed flat against a leaf when alarmed, it becomes hard for predators to pry loose from the edge.

Key figures

Length

About 6–8 mm; round and flat like a miniature tortoise shell

Life cycle

Multiple generations a year in warm regions; adults can live for several months

Habitat

Sweet potato fields and the leaves of other morning glory family (Convolvulaceae) plants

Diet

Both adults and larvae feed on the leaves of sweet potato and other Convolvulaceae plants

Defense

The flared translucent margin covers its head and legs; pressed flat against a leaf, it is hard for predators to pry loose

Camouflage

Larvae pile their shed skins and droppings onto a forked tail process, holding them aloft like a protective parasol

Life cycle

Egg → Larva (carries shed skin and droppings) → Pupa → Adult

Ecological role

Both adult and larval Sweet Potato Tortoise Beetles feed on the leaves of sweet potato and other Convolvulaceae plants. They are common but only mildly damaging in sweet potato fields, and a textbook example of the defensive structures found across the tortoise beetle subfamily (Cassidinae).

Did you know

Some tortoise beetle larvae stack every shed skin and dropping onto the forked tail process on their back, raising a body-covering "fecal umbrella" whose sole purpose is to confuse the eyes of predators.

Range

Sweet-potato-growing regions of southern and central China, and East to Southeast Asia

Status

Common; a minor pest in sweet potato fields

Anatomy

• Skirt margin — The translucent flared edge of the elytra and pronotum, the feature that gives tortoise beetles their name
• Elytra — Domed like a shell, often patterned with spots or variable coloring
• Head — Tucked beneath the pronotum, almost entirely hidden when alarmed
• Compound eyes — Small and inconspicuous, hidden in the shadow cast by the flared margin
• Legs — Short; when pressed flat against a leaf, they are covered by the margin along with the head
• Pronotum — Its edge likewise flares into a skirt that meets the elytra's margin, fully enclosing the beetle

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