Armyworm

AVRDC
Crop Protection Guides

Soybean Insect Pests

Armyworm
Spodoptera litura

Found worldwide

Damage symptoms

Chewed holes are present on the leaves. Leaves are damaged to the point that they are not recognizable as those of soybean. In severe infestations, leaves are completely gone causing the plant to die. Occasionally this insect also cuts plant stems at the soil line and feeds directly on the pods.

Insect characteristics

Chewing mouthparts. Very young caterpillars are blackish-green and have a distinct black band across the back of their heads. Older ones are slightly darker with yellow bands along their backs and sides of their bodies. Their heads are prominent and black and along their backs are rows of crescent-shaped black spots. Adult moths are active only at night.

Defoliated field

Pupae insoil

Where to look

They are easy to detect. The young larvae feed together on the surface of the leaves. Larger caterpillars tend to feed along. Search the entire plant to locate them. Look carefully at the upper and lower surfaces of the leaves.

Technical information

The behavior of this species is variable (Note above paragraph). Females lay their eggs in hair-covered clusters. Mature caterpillars pupate in earthen cells in the soil. Generations may be continual in warm climates. This insect attacks many species of crops. Among them are tomato, cauliflower, potato, onion, eggplant, chili pepper, lettuce, pea, and maize.

Control

Insecticides are used to control this pest. Defoliation during the mid-flowering stage is most damaging to yields. Pheromones may be used to monitor pest populations. Resistant lines are being developed.

Last updated: 2001.
Information from: Field Guide: Insect Pests of Selected Vegetables in Tropical and Subtropical Asia. 1995. B.L. Parker, N.S. Talekar and M. Skinner. Publication 94-427. Pesticide and other control recommendations should be adapted to local conditions.

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