Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

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Grass leaf beetle (354)

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Photo 1. Adult leaf beetle, Oulema species.

Photo 2. Hump-backed, black 'blob' of the larvae of Oulema species from Fiji.

Photo 3. Damage by the leaf beetle, Oulema species to crowsfoot grass, Eleusine indica.

Photo 4. Damage by the leaf beetle, Oulema species, to barnyard grass, Echinochloa crus-galli.

Summary

• Unknown distribution. Recorded only from Fiji on two weeds: crowsfoot and barnyard grasses. The Oulema species unknown. Another species, Oulema melanopus, is recorded from Asia, Africa (north), North America, Europe, as a major pest of cereals.
• Eggs laid on leaf mid-vein; larvae hump-backed, covering themselves in faecal matter. Pupate on soil. Adults with red heads and thorax and black wing cases; often seen 'mate-guarding'.
• Larvae feed on the surface of leaves setting back plant growth so that the grasses are overgrown by other weed species. Damage greatest on crowsfoot grass.
• No control measure required. Whether or not the beetles will move to other grasses, i.e., those of the grasslands of western Viti Levu, Fiji, is unknown.
• Alternatively, the Fiji Oulema species may have potential as a biocontrol organism attacking  particular weed grasses.

Common Name

Leaf beetle, grass leaf beetle (not an accepted common name).

Scientific Name

Oulema species. The Oulema species recorded from Fiji has not been identified. However, the cereal leaf beetle (oat leaf beetle), Oulema melanopus, is a major pest of wheat, barley, oat, and millet, worldwide. In countries where it is not yet present, it is considered a pest of quarantine importance. For these reasons, the Fiji species is described here.

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