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Lesser armyworm
- Lesser armyworm. Photo: N. Forrester.
General information
Armyworms owe their name to the observation that larvae sometimes march in large numbers away from sites depleted of food. Adults of some species sometimes undertake long distance migrations at night.
| Scientific name | Spodoptera exigua |
|---|---|
| Description | The moth is about 10 mm in length with grey, mottled forewings. The hindwing is a pearly-white colour. Eggs are laid in rafts of 10 to 30, covered by webbing-like scales, by the female moth, similar to the cluster caterpillar. The young larvae remain near the egg raft and skeletonise. The mature larvae are often mistaken for helicoverpa spp. but are green to brown, with a white stripe along each side of the back. They are half the length of a mature helicoverpa larva. |
| Similar species | Various armyworms and helicoverpa. |
| Crops attacked | Prefers weed hosts, but is often present in low numbers on young cotton. |
| Damage | Larvae may occasionally infest seedlings heavily enough to cause defoliation. Resowing may be necessary. |
| Monitoring and action level | The threshold for control is two small larvae or one large larvae per metre from emergence to flowering. See Pest Genie or APVMA for current control options. |
Further information
- Crop insects: The ute guide - Northern Grain Belt Edition
- Pests of field crops and pastures: Identification and control Editor: P.T. Bailey.
Author: Moazzem Khan
Page maintained by Sue O'Brien
Last updated 10 February 2010