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Common Name: Fall armyworm Scientific name: Spodoptera frugiperda (J. E. Smith)
Adult moths are about 1 inch long with gray-brown sculptured front wings and whitish hind wings. Females lay egg masses on leaves of rice and other grasses in and around rice fields. The larvae emerge and begin feeding on rice plants. Larvae vary from light green to brown to black, with distinctive white stripes along the body. Mature larvae are about 1 inch long and have a distinctive inverted “Y” on the head. Larvae feed for two to three weeks, developing through five instars. Mature larvae pupate in soil or decomposing plant material. Moths emerge from the pupal casing in one to two weeks, mate and disperse widely.
Damage caused by larva: Fall armyworm larvae feed on the leaves of young rice plants, destroying large amounts of tissue. Seedlings can be pruned to the ground, resulting in severe stand loss. The fall armyworm feeds on most grasses found in and around rice fields. It is also a serious pest of corn and pasture grasses.
Facts: Fall armyworm is an occasional pest on rice. Fall armyworm larvae feed on the leaves of young rice plants, destroying large amounts of tissue. Seedlings can be pruned to the ground, resulting in severe stand loss. Fall armyworms infest field borders, levees and high areas of fields where larvae can escape drowning. They are more likely to be a problem in late-planted fields and in fields surrounded by pasture.
What should you look for: After germination of seedlings, scout fields weekly for larvae on plants. Mature larvae are about 1 inch long and have a distinctive inverted “Y” on the head. Birds are often attracted to fields infested with armyworms. If you see large flocks of birds in your field, you should take the time to scout for armyworms.
How you can manage fall armyworms: Sample plants every 10 feet along a line across the field, and repeat this process in a second and third area of the field. Treat when there is an average of one armyworm per two plants. Reduce larval infestations by effective management of nearby grasses. Flood infested fields for a few hours to kill fall armyworm larvae.