Army Worm

16 May, 2023

Armyworm is the common name for the larval stage of the noctuid moth Spodoptera frugiperda which blew into NZ in early 2022 and is now widespread in the North Island.

Armyworms are caterpillars of a small light brown moth that flies about at night laying its eggs in the soil. Once the caterpillars emerge from the soil, they munch away on young plants and seedlings chewing the stem at the base.

Caterpillars grow up to 40mm long and come in various colours, including light grey, black, pinky-brown. When disturbed, they curl up into a coil.

Not easy to see during the day as they come out at night to feed, and hide in the daylight hours in the soil.

After periods of rain and warm conditions, they can become very active, even in plaque proportions.

There are various species of Armyworm that affect commercial and home gardens, the main ones being The Fall Armyworm (FAW) and the Tropical Armyworm. Click the link below for further information on identification.

Natural Treatment

Adults hide during the daytime; ground migrating larvae may hide under crop cover and in the soil. These behaviours allow this pest to go undetected.

In summer start spraying as a preventative measure by spraying with either Aquaticus Bugtrol, Yates Pyrethrum or Bioneem.

Spray at weekly intervals for best control, alternating sprays will give a better result and reduce the chance of the pest developing a resistance to any one spray.

At night when they are active go outside with a torch and collect as many of the caterpillars as possible and dispose of them.

Cover crops with Bugnet which will help prevent the Moth being able to lay eggs. Make sure that the net is not resting on the plants but is raised up or the moth will still be able to lay.

Apply Native Neem Granules to the soil in vegetable gardens to help control the caterpillar hiding in the soil.

Other Treatment

For best control early intervention is best practice, better still spray as a preventative measure.

Spray with a combination of the following sprays and treatments. Alternating sprays will give a better result and reduce the chance of the pest developing a resistance to one spray.

Success Ultra this spray can be only used 4 times in any one season this is to avoid the pest from building up a resistance.

Bioneem apply this spray at 7-10 day intervals throughout the growing season, even when pests are not present. Alternate this spray with either Bugtrol or Yates Pyrethrum.

Treat Lawns with Kiwicare Lawn Pro Protect to get at larvae in the soil. No not use this product in vegetable gardens or around fruit trees.

When using sprays and chemicals always follow the label instructions carefully.

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