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Armyworms

Early instar armyworms have been detected in an oat crop south of Ararat, in the Western district of Victoria. Agronomist, Craig Drum (Tatyoon Rural), reports finding very low numbers of caterpillars when sampling with a standard sweep net, and says there are no signs of any feeding damage to the crop at this stage. Armyworms (Family: Noctuidae) may attack cereal crops and grass pastures, and are usually most damaging toward the end of spring when crops are close to harvest. The larvae chew through the last remaining green part of the plant stems (just below the head), causing the heads to drop off. Given the low numbers and small size of these caterpillars, it is unlikely that they will have any significant impact prior to the crop being harvested.

Armyworms have three parallel white stripes running from the ‘collar’ behind the head, along the body to the tail end, making them easily distinguishable from cutworms and native budworm, with which they are sometimes confused. They also have large heads and smooth, fat bodies that are usually pinkish, green or brown in colour. They can grow up to 40 mm in length. Adult moths are grey-brown in colour and have a stout body with a wingspan of approximately 40 mm.

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