Japanese Green Dock Beetle (Gastrophysa atrocyanea) — identification, habitat & look-alikes

The Japanese Green Dock Beetle is a tiny, dark blue leaf beetle found in East Asia. It feeds on docks and sorrels there; in the United States, a similar beetle on dock is the green dock beetle (Gastrophysa cyanea).

Appearance

Appearance: Adults are about 0.22 in (5.5 mm) long and glossy dark blue to blue-black. The larvae are black with small bumps along the back and sides.

Look-alikes

green dock beetleGastrophysa cyanea

Both are small metallic beetles that feed on docks and sorrels. In North America, the green dock beetle is the expected species, while the Japanese Green Dock Beetle is East Asian; close photos may still require expert review.

Why they get mixed upThey share a shiny blue-green look and the same host-plant group.

Where it lives

Typical habitats: grassy places with docks in East Asia
Range: This species is found in East and parts of Southeast Asia. The green dock beetle occurs across much of North America.
Preferred conditions: It stays near docks and sorrels.

Behavior

Diet: In its Asian range, adults and larvae eat leaves of docks and sorrels.
Social life: In Japan, larvae have been observed feeding together on leaves.
Overwintering: In Japan, adults survive the winter.

Life cycle

Reproduction: The species has through egg, larva, pupa, and adult stages.
Larva: In Japan, larvae feed on leaves, then enter the soil to become pupae.

Conservation

IUCN Red List: NENot EvaluatedNot yet assessed

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