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Armyworms

We recently identified armyworm caterpillars from a wheat crop south of West Wyalong, in the South West Slopes district of New South Wales. Agronomist, Terry Edis (Elders), reported finding a low number of caterpillars along with some chewing damage on the leaves of the crop. The caterpillars found were approximately 20 mm long, but can grow to about 40 mm in length. Despite the damage, control is not necessary at this stage. Instead the paddock will be monitored in the coming weeks to see whether caterpillar numbers increase. The first visible sign of armyworm caterpillars is often their green to straw-coloured droppings, about the size of a match head, found on the ground between crop rows.

Armyworms (Family: Noctuidae) are most easily identified by the presence of three parallel white or cream coloured stripes running from the ‘collar’ behind the head, along the body to the tail end. They have the potential to be very damaging toward the end of spring when crops are close to harvest. This is because they chew through the last remaining green part of the plant stems (just below the head), causing the heads to fall. Where warranted, treatment for armyworms should ideally be carried out in the late afternoon or early evening as feeding activity is often during the night.

Click here for images of armyworms and refer to PestFacts Issue No. 6 for further information.

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