Summary

Restricted. Asia, Oceania. In American Samoa, Australia, Fiji, French Polynesia, Guam, New Caledonia, Northern Mariana Islands, Papua New Guinea. Samoa, Solomon Islands.
In Asia, minor rice pest; in Fiji, major pest on high-yielding varieties beginning in 1970s. Also on maize, wild grasses.
Larvae eat inside tunnels of folded or bound leaves, creating long white stripes. Fields appear grey.
Eggs laid singly or in small groups, overlapping in rows, often on tallest plants. Larvae yellowish-green with pale-brown heads, up to 11 mm, feed together initially then disperse. Pupate on leaves. Adults pale-yellow wings with grey-brown borders, wingspan 13 mm, with 3-4 bands.
Natural enemies: many egg and larval parasitoids and predators. In Fiji, Trichogramma and Trathala flavo-orbitalis destroy >40% of larvae.
Biosecurity: introduction possible on produce contaminated with infested stems of host plants.
Cultural control: increase plant spacing; fallow land or rotate crops; do not over-fertilise; remove weeds within and around crops; do not ratoon crops; flood fields after harvest or plough in straw and stubble; resistant varieties (new, high-yielding varieties susceptible).
Chemical control: use neem, abamectin, or spinosad. Avoid broad-spectrum products.

Common Name

Rice leaf roller

Scientific Name

Marasmia exigua. It is also known as Cnaphalocrocis exigua, Samea exigua, and Susumia exigua. A moth in the Crambidae.

AUTHOR Grahame Jackson
¹Information from Singh SR (1997) Biology of the rice leafroller Cnaphalocrocis (Marasmia) exigua (Butler) (Lepidoptera): Pyralidae: Pauristinae) in Fiji. PhD Thesis. Faculty of Science, Technology and Agriculture, University of Western Sydney, Australia; and Phathak MD (1975) Insect pests of rice. The international Rice Research Institute. 3^rd printing; and from CABI Marasmia exigua (rice leaf roller) (2018) Crop Protection Compendium. (https://www.cabi.org/cpc). Photos 1&2 Rice-feeding insects of Tropical Asia. IRRI Photos. Flickr. (https://www.flickr.com/photos/ricephotos/6676485397).

Produced with support from the Australian Centre for International Agricultural Research under project HORT/2016/185: Responding to emerging pest and disease threats to horticulture in the Pacific islands, implemented by the University of Queensland and the Secretariat of the Pacific Community.

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