Protect your Lawn: Armyworm Facts and Fixes

Impact of Lawn Caterpillars

Lawn Caterpilars are commonly referred to as armyworms, especially when they appear in large numbers and behave in a coordinated way that resembles an invading army. The term "armyworm" refers to their feeding behaviour. They march across turf and crops in large numbers, striping foliage as they go. Their movement is highly destructive and often appears sudden, which can look like a coordinated "invasion".

Armyworms are found across Australia, particularly during late summer or early autumn, when conditions are warm and humid. They are most active at night and hide during the day in thatch or soil. In the lush expanse of a well-manicured lawn, a silent invasion often goes unnoticed until it's too late. Lawn caterpillars have voracious appetites. They can transform a vibrant green carpet into a patchwork of brown and bare spots almost overnight. These pests feed on leaves and stems. This results in reduced yield and can even kill young plants.

The fall armyworm, first detected in Australia in 2020, has become a significant concern. Its rapid spread and resistance to many insecticides make it particularly troublesome. In urban and recreational areas, people refer to them as lawn grubs or lawn caterpillars. They are known for damaging grass by chewing leaves down to the crown.

For pest control professionals, understanding the lifecycle and behavior of these stealthy pests is critical. By identifying the early signs of infestation and implementing timely control measures, you can protect your clients' lawns. This helps maintain their pristine appearance.

Understanding the lifecycle and behaviour of armyworms is critical to control this pest.

Lifecycle and Behavior

These caterpillars are most active from late spring to autumn (October to April on the Eastern Coast of Australia). Moth activity increases after rainfall or irrigation, which can then trigger egg-laying. Lawn caterpillars feast on grass, leading to brown patches and thinning lawns.

It's essential to note that, despite their potential for damage, lawn caterpillars play a vital role in the ecosystem. They serve as a food source for various predators, including birds, beneficial insects, and small mammals. This predation helps maintain a balanced ecosystem, supporting biodiversity.

When Armyworms Become a Pest

Lawn caterpillars can transition from a minor presence in your lawn to a significant concern under specific conditions. Understanding when they become problematic and how to address them is crucial for maintaining a healthy lawn.

Lawn caterpillars are the larva stage of several moth species and feed on grass blades, causing rapid and widespread damage to turf.

Warmer temperatures and elevated humidity levels, typical of the subtropical regions along Australia’s eastern coast, can accelerate the development and reproduction of lawn caterpillars. Their eggs hatch within just a few days, and the caterpillars feed voraciously, particularly in late summer. These climatic conditions create an ideal environment for their rapid growth. This often results in more frequent and severe infestations. The damage not only leaves lawns looking unsightly but also makes them more vulnerable to other pests and diseases.

The economic impact of the damage caused by lawn caterpillars can be significant. Homeowners face increased costs for lawn repair and maintenance.

Strategies to detect Armyworms

1. Visual Inspection: Look for chewed grass blades, bare patches, or scalloped edges in your lawn. Caterpillars are most active at dusk or early morning, often hiding during the day.

2. Easy and effective soap-flush: Mix 2 tablespoons of dish soap in 4 liters of water. Pour the mixture over a small area (1 m²) of the affected lawn. Wait 5-10 minutes. If lawn caterpillars are present, they will surface quickly.

Prevention:

• Maintain a Healthy Lawn: Mowing regularly, but not too short is important. Longer grass can tolerate more feeding. Water deeply but infrequently to encourage strong roots. Fertilize appropriately, especially in spring and early summer.

• Monitor Regularly: It is prudent to monitor caterpillar activity, especially during warmer and wetter months when infestations are more likely. Implementing pest management (IPM) strategies that consider climatic conditions can enhance pest control efforts. Check for signs of moth activity; they flutter low over the grass and lay eggs. Additionally, use a light trap or monitor bird activity, as they feed on the caterpillars.

• Biological Control: Birds such as magpies, mynas, robins, and starlings can act as natural biological controls for armyworms. However, they are just one part of several beneficial organisms used in integrated pest management strategies.

When to Call a Professional

1. If the infestation is widespread, recurring, or causing severe damage.

2. If you prefer organic or targeted pest control strategies with minimal environmental impact.

3. When uncertain about the correct pesticide application.

   
   

Summary of Key Strategies

Ultimately, research findings support the development of sustainable pest management strategies to control armyworm infestations. The implications of such studies extend beyond agriculture and offer valuable insights for urban pest control strategies that prioritise maintaining ecological balance.

Being proactive is key to managing armyworms, and given the right approach, your lawn will thrive despite the potential of these pesky invaders.