How to Catch Lawn Grubs Before They Catch You

Lawn grubs can cause serious damage to an otherwise healthy lawn, often without you noticing until it’s too late. Because they live below the surface feeding on the roots, the first signs usually don’t appear until the grass begins to struggle.

The good news is that if you know what to look for, you can often catch lawn grubs before they cause widespread damage. Regular inspections and early treatment can save you from having to repair large sections of your lawn later.

Lawn grubs are the larval stage of several scarab beetles that are found throughout Australia. Species such as African black beetle, Argentine scarab and Christmas beetles all spend part of their life underground as white, C-shaped grubs.

Unlike caterpillars that feed on the leaves of your lawn, lawn grubs live in the soil where they feed on the roots. As they grow, they reduce the lawn’s ability to absorb water and nutrients, causing the grass to weaken and eventually die if left untreated.

Adult beetles lay their eggs in the soil during the warmer months. Once the eggs hatch, the young grubs begin feeding on the roots before eventually pupating and emerging as beetles to continue the cycle.

Because lawn grubs are hidden underground, the damage they cause is often mistaken for drought stress or a lack of fertiliser.

Some of the most common warning signs include:

- Brown patches that continue to spread despite watering.

- Grass that feels soft or spongy underfoot.

- Sections of lawn that pull up easily like loose carpet.

- Wilting during warm weather even when the soil is moist.

- Birds digging in the lawn searching for grubs.

- Thin or dying turf with very little root growth.

These symptoms usually become more noticeable as the grubs grow larger and consume more roots.

The best way to confirm lawn grubs is to inspect the soil rather than relying on surface symptoms alone.

Using a shovel, cut three sides of a square approximately 30 cm by 30 cm and carefully lift the turf back. Inspect the root zone and the first few centimetres of soil for cream-coloured, C-shaped grubs.

Healthy lawns may occasionally contain one or two grubs without suffering noticeable damage. However, finding several grubs within a small area, particularly where the lawn is already declining, usually indicates it’s time to take action.

Checking several locations around affected areas will give you a much better understanding of how widespread the infestation is.

Knowing when lawn grubs are most active can help you stay one step ahead.

Adult beetles generally emerge during spring and summer before laying eggs into the soil. After hatching, the young grubs begin feeding on the roots throughout the warmer months while gradually increasing in size.

As temperatures cool, many species slow their feeding before eventually pupating and emerging as adult beetles to repeat the cycle.

The exact timing varies depending on the species and where you live in Australia, but regular inspections throughout spring and summer are the best way to catch problems early.

Once lawn grubs have been confirmed, treating them sooner rather than later will minimise damage to your lawn.

Preventative treatments are generally the most effective option because they target young lawn grubs before they have the opportunity to cause significant root damage. Applying a preventative insecticide before peak grub activity can provide long lasting protection throughout the season.

If your lawn is already showing symptoms and grubs are present beneath the surface, a curative treatment may be required to reduce the existing population before further damage occurs.

Always follow the product label carefully to ensure the best results and water products in.

In many cases, yes.

If lawn grubs are detected early and treated before extensive root damage has occurred, warm-season grasses such as couch, kikuyu, buffalo and zoysia often recover well once new roots begin developing.

Continue watering appropriately, avoid unnecessary stress from heavy traffic and maintain a balanced fertiliser program to encourage recovery.

If sections of turf have completely died, small repairs or re-establishment may be required after the grub population has been controlled.

While no lawn is completely protected, there are several ways to reduce the chances of a serious infestation.

Regularly inspect your lawn during spring and summer, particularly if you’ve experienced lawn grubs in previous years. Watch for unusual brown patches, thinning turf or birds frequently feeding in the same areas.

Applying preventative treatments before young grubs become established can dramatically reduce future damage, while maintaining a healthy lawn allows it to recover more quickly if some feeding does occur.

Early detection of lawn grubs will almost always result in a better outcome than waiting until large areas of lawn have already declined.

Lawn grubs are one of the few lawn pests that attack from below the surface, making them easy to miss until significant damage has already occurred. Fortunately, a simple inspection beneath the turf can quickly confirm whether they’re responsible.

By understanding their life cycle, recognising the early warning signs and checking your lawn regularly during the warmer months, you can catch lawn grubs before they catch you. A few minutes spent inspecting your lawn each season can prevent months of unnecessary recovery work.