Lawn Armyworm
Botanical name: Spodoptera mauritia
Common Names
Also known as: lawn armyworm, lawn grub, paddy swarming caterpillar
Lawn Armyworm Description
The lawn armyworm, a significant pest of turf grasses and a variety of crops, is characterised by its voracious feeding habits. This pest is particularly notorious for its ability to rapidly damage lawns, pastures, and crops, making it a critical concern for both agricultural and residential lawn care. The larvae, or caterpillars, are the primary stage of concern, as they are the ones who feed on the vegetation.
Larvae & Feeding Habits
The larvae are initially light green or yellow, becoming darker with age, and can grow up to 40 mm in length. They are marked by distinct stripes running longitudinally along their bodies. These caterpillars are highly mobile and known for their "army-like" movement across surfaces as they consume the foliage in their path. Their feeding can result in significant damage to lawns and crops, often leaving behind bare patches or significantly thinned vegetation.
Adult Armyworm & Reproduction
The adult lawn armyworm is a moth, greyish-brown in colour, with a wingspan of about 40 mm. The moths are nocturnal and attracted to light. They lay their eggs in clusters on the leaves of host plants, which hatch into the damaging larval stage. The rapid life cycle and high reproductive rate of the lawn armyworm allow for multiple generations within a single season, contributing to its potential for widespread infestation.
Armyworm Control & Management
Management of lawn armyworm infestations involves a combination of monitoring, cultural practices, and chemical control. Regular monitoring of lawns and crops for the presence of larvae and damage can help in early detection and timely intervention. Cultural practices, such as maintaining healthy lawns and crops through proper fertilisation and watering, can reduce the impact of armyworm damage. When necessary, chemical control options are available, but should be used judiciously and in accordance with local regulations to manage populations effectively while minimising environmental impact.
Similar Pests
The lawn armyworm is often confused with other caterpillar pests, such as the cutworm and the sod webworm. However, its "army-like" feeding behaviour and the characteristic longitudinal stripes on the larvae help distinguish it from these other pests. Additionally, the lawn armyworm's preference for a wide range of host plants, including many types of grasses and crops, sets it apart from pests with more specific feeding habits.
The lawn armyworm poses a significant threat to lawn and crop health through its aggressive feeding behaviour. Effective management requires vigilance, prompt action, and a combination of cultural and chemical control strategies to mitigate damage and prevent widespread infestation.
Not sure if you have lawn grubs? Try this quick test:
- Mix a couple of squirts of detergent with a bucket of water.
- Pour it over a section of lawn where you suspect damage.
- Watch for grubs to wriggle to the surface within a few minutes!