Grass looking sad because of lawn caterpillars? Here’s how to fix it

Lawn caterpillars can cause huge damage to your beautiful green lawn if left untreated. These pests are the larvae of moths, and they feed on your grass at night, leaving ugly brown patches behind. Spotting and controlling these pests early is key to saving your lawn from severe damage.

In this article, we’ll explore what they are, how to spot them, and what you can do to keep your grass healthy and green.

What are lawn caterpillars?

Lawn caterpillars are typically 20–30 mm long and are a green-brown colour. Though small, these caterpillars can cause big problems for your lawn, particularly in the middle to late summer when they’re most active.

They gnaw on the grass blades, stems, and even roots, which results in dead patches on your lawn. If you notice brown patches starting to appear, lawn caterpillars could be the culprit.
You might not see them during the day, but the damage they cause will be hard to miss. Here’s how to detect their presence:

  • Discoloured grass: Early on, look for small discoloured spots on the grass blades.
  • Brown patches: As they mature, lawn caterpillars will start attacking the grass roots, causing larger brown patches to appear on your lawn.
  • Holes in plants: If you have bedding plants nearby, you might also notice holes in the leaves where the caterpillars have been feeding.

Lawn showing a mix of healthy green grass and brown patches caused by lawn caterpillar damage.

To confirm that lawn caterpillars are responsible, try placing a damp towel over a brown patch overnight. In the morning, if caterpillars are the problem, you’ll likely find some stuck to the towel’s underside.

Controlling lawn caterpillars

Catching and controlling lawn caterpillars early will save you a lot of hassle. Here are some methods to help you combat these pests:

1. Preventative measures

  • Mow your lawn regularly: Caterpillars feed on the new growth of grass. By mowing often, you’ll prevent excessive growth and make it harder for them to feed. Be sure to discard the clippings far from your lawn to avoid spreading the infestation.

Detailed view of a spiky brown lawn caterpillar feeding on a plant stem.

2. Direct treatment

Wonder Lawn Pest & Green is an excellent option. It’s designed specifically for lawn caterpillar control and is also a fertiliser that feeds and strengthens grass.

  • How to use Wonder Lawn Pest & Green: Apply 60 g per m² of lawn when you spot an infestation of caterpillars. You can repeat this treatment every four weeks if necessary, but be careful not to overuse it. After application, water your lawn thoroughly.
  • Safety Precautions: When using any insecticide, it’s essential to follow safety guidelines. Wear gloves, avoid inhaling the dust, and wash thoroughly after handling. Keep the product away from children and pets, and store it safely.

Additional lawn care tips

While controlling lawn caterpillars is important, adding a few extra steps to your routine will help keep your lawn looking its best year-round:

  • Use a balanced approach to fertilising to keep your lawn healthy without encouraging pests. Wonder Lawn Booster is a high-quality slow-release fertiliser for use throughout the year. 
  • In water-scarce conditions, it’s essential to be mindful of your lawn’s water usage while still keeping it healthy. Instead of frequent shallow watering, focus on deep watering once a week. This encourages deep root growth, making your grass more drought-resistant and better equipped to handle pests. Water early in the morning or late in the evening to reduce evaporation, and consider using rainwater or greywater where possible to conserve resources.

Vibrant, healthy green lawn under the golden sunlight.

You may also be interested in: Stop searching “How to revive dying grass?!” – This guide has ALL the solutions

By keeping an eye out for the signs of lawn caterpillars and following these control methods, you’ll be able to protect your lawn and keep it looking green and healthy. Follow us on Instagram and Facebook for more garden care advice. 

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