Lawn armyworm (Spodoptera Mauritia) is a damaging pest when in the larval life stage. The larvae are a soft-bodied caterpillar with a dark-coloured body up to 45 mm long. They possess unique white and yellow striped patterns along the length of the back making them relatively easy to identify.

When feeding the larvae often appear in congregations, clumping around stems and foliage of the turf plant.

Once mature, the caterpillar metamorphoses into a pale brown moth with a wingspan up to 40 mm and possesses a distinct white spot in the centre of the fore-wing.

The newly hatched armyworms stay together, feeding on the same plant until it is devoured. The larvae lawn armyworm are usually most active in the evening or at night, except in overcast weather conditions. During the day they hide under the safety of the lower grass leaves.

An armyworm will undergo six to nine instar stages before it is fully developed. This will take 21 to 35 days and at a mature instar stage the insect will reach 3 to 4 cm in length. When fully fed the armyworm will work its way into the soil profile where it pupates. Ten to 14 days later the moths emerge. There could be two to three generations of armyworm during the summer/autumn period.

If you need help with turf insect identification, message the friendly team at Lawn Addicts. We can help select the best insecticides and online lawn care products, based on your turf.

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