Is your lawn turning brown? Grubs might be the cause. They eat grass roots, so the grass can’t absorb water from the soil. If you want to save your landscape, you have to learn how to get rid of grubs in your lawn. To tackle the problem, use chemical insecticides, beneficial nematodes, milky spore, neem oil, lawn-aerating shoes, or birds.
What are grubs and what do they do to your lawn?
Grubs are “C”-shaped insects with soft, white to grayish bodies and a distinct brown or tan head. They’re legless and have a series of fine spines near their back end, known as the rastral pattern. Grubs grow to about 1 to 2 inches long and are the larvae of various beetle-type insects, including:
- Japanese beetles
- Masked chafers
- European chafers
- Billbugs
- June bugs
They begin as eggs in the soil, which hatch into larvae. The larvae, or grubs, feed on roots and organic matter until they pupate. After several weeks as pupae, they emerge as adult beetles.
Grubs prefer various habitats, including soil, decaying organic matter, and plant roots. If you have a grub problem in your lawn, you might notice:
- Wilted grass
- Spongy turf
- Small, irregular brown spots
- Dry, dying patches of grass
- Wildlife such as raccoons, skunks, and armadillos digging holes into the ground (looking for grubs)
- Large patches of grass easily lifting out of the ground
- Increased thatch due to grub-feeding habits
To test for grubs, dig up a section of grass from the browning area about 1 square foot large and 2 to 3 inches deep. If you have grubs, you’ll easily spot them. Count the grubs; any number above 10 per square foot counts as an infestation.
6 ways to eliminate grubs in your lawn
Left unchecked, grubs can destroy your lawn. Act early to remove them and prevent future infestations.
1. Chemical insecticides
You can buy insecticides from your local garden center to eliminate and prevent grubs in your lawn. But remember that their chemical composition brings significant downsides:
- Can hurt pollinators
- Can pollute groundwater, lakes, rivers, and other water sources
- Can poison children or pets that come in contact with the chemical or treated area
- Can reduce beneficial insect populations, making your grub problem worse
Chemical grub control should be your last resort. Choose an insecticide with the active ingredients carbaryl or trichlorfon and apply it only when you know you have many active grubs in your lawn. Typically, grubs are young and actively feeding close to the soil surface in late July to early September.
How to use granular insecticides:
- Choose a clear, wind- and rain-free day.
- Wear protective gear (safety goggles, gloves, and a face mask).
- Select a drop or broadcast spreader (a common lawn care tool you can find online or in garden supply stores).
- Fill the spreader with the granules and adjust the flow rate according to the label instructions.
- With a steady pace, cover the entire lawn as evenly as possible. If you encounter obstacles like trees or shrubs, turn the spreader off until you’ve passed them. Overlap your passes slightly to prevent gaps.
- Water the area to activate the insecticide and follow the label instructions. Some products require more water than others.
How to use liquid insecticides:
- Choose a clear, wind- and rain-free day.
- Wear protective gear (safety goggles, gloves, and a face mask).
- Apply liquid insecticides using a hose sprayer. Some insecticides already come in a hose spray bottle, but if yours doesn’t, check the label for the correct concentration of insecticide to put in the hose sprayer.
- Attach the sprayer to the end of any standard garden hose.
- Spray the mixture across your whole lawn, row by row. Try not to miss any spots or use too much, as the liquid may run into other areas.
- Check the label for watering instructions. Some liquid insecticides require water for absorption, while others don’t.
2. Beneficial nematodes
These eco-friendly biopesticides (small worms) enter the grubs and kill them by releasing bacteria. They safely reduce grub numbers without harming nearby plants or animals.
The Heterorhabditis bacteriophora and Steinernema feltiae varieties reproduce on their own and can keep grub populations in check for years. One caveat: it can take up to three years to significantly eliminate your grub problem.
How to use beneficial nematodes:
- Choose an overcast, but wind- and rain-free day, or apply them in the morning or evening. Sunlight and high temperatures can kill them before they can reach the grubs.
- Wear gloves.
- Since these are live organisms, introduce them to the lawn soon after purchasing them.
- They love moisture, so water the lawn before and after application (unless the ground is already wet from rain). Keep the soil consistently moist for optimal effect.
- Re-apply them every 2 to 3 weeks until you notice results.
3. Milky spore
Milky spore is a bacterium that comes in powder or granular form and targets Japanese beetle grubs (they have a pointed end, whereas other grubs are rounded). It’s an old and popular method, but it takes up to three years to work fully.
When grubs eat the spores from the grassroots, they get infected and die. The dead grubs release more spores into the soil, spreading the bacteria and controlling grubs long-term.
Milky spore may not be as effective in very dry or wet soils, or in colder climates. Its initial cost is also higher, but it provides long-term results.
How to use milky spore:
- Choose a clear, wind- and rain-free day.
- Wear protective gear (safety goggles, gloves, and a face mask).
- For powder, use a funnel to fill a garden dispenser. You’ll need a teaspoon of the powder for every 4 feet of lawn. If you’re using a drop spreader for granules, park it on a flat surface, ensure it’s dry, and fill the hopper with the granules.
- Apply milky spore when the soil is between 60 and 70 degrees Fahrenheit, walking in a consistent pattern for even coverage. Since milky spore is lightweight, don’t use a broadcast spreader to apply it, as the wind will blow it away.
- Lightly water the treated areas to help the spores penetrate the soil.
4. Neem oil
Neem oil is a natural pesticide that directly affects how grubs grow and develop. It doesn’t kill them outright but makes it difficult for them to survive. Plus, it doesn’t harm plants, animals, or beneficial insects, so it’s an eco-friendly way to control grubs.
Neem oil is available as raw neem oil, which has the insecticide azadirachtin, and clarified hydrophobic neem oil, which doesn’t.
The clarified version, commonly sold in stores, is less potent than the raw version but can still suffocate grubs in the soil. It coats the insects and cuts off airflow.
Raw neem oil contains every active component naturally present in neem seeds, is thicker, has a stronger odor, and is often used in organic farming. It’s the most effective option of the two.
How to use neem oil:
- Choose a clear, wind- and rain-free day.
- Wear protective gear (safety goggles, gloves, and a face mask).
- You can either purchase a neem oil spray or make one yourself with this recipe:
- Mix ⅓ teaspoon of mild or natural soap (like Castile soap) into 1 quart of warm water. Shake well.
- Add 1 teaspoon neem oil to the mixture and shake well again.
- Pour it into a sprayer and apply it to your lawn to suffocate the grubs.
5. Lawn-aerating shoes
Use lawn-aerating shoes to poke the soil, disturb the grubs, and eliminate them. This helps other grub treatments penetrate the soil and spread more effectively.
Some considerations: Lawn-aerating shoes may not reach deep enough to kill the grubs, and it’s also hard to cover the entire lawn evenly.
How to use lawn-aerating shoes:
- Choose a clear, wind- and rain-free day.
- Put on the shoes and walk across your lawn a few times, concentrating on areas with severe brown patches.
- As the spikes create small holes in the soil, they help to expose and disturb the grubs.
- Next, apply an appropriate grub control treatment that can penetrate the soil thanks to the holes created by the shoes.
- Water the treated areas to accelerate the treatment effect.
6. Birds
Grub infestations naturally attract birds, which can eat grubs and prevent beetles from laying eggs on your lawn.
How to attract birds to your yard:
- Set up bird feeders and install nesting boxes
- Place birdbaths around the yard as a fresh water supply
- Plant shrubs and trees to provide shelter
- Remove thatch and other debris to expose the grubs and other insects, making it easier for the birds to spot and eat them
- Limit outdoor pet presence that could scare the birds
- Avoid using chemicals as much as possible (for the health of your landscape as well as the birds)
How to prevent grubs
Grubs tend to heavily infest a region for about five to 10 years, so you may be busy for several seasons if you have them. To prevent future grub attacks:
- Around June, apply preventive systemic insecticides containing thiamethoxam, clothianidin, and imidacloprid for long-lasting grub control. Local regulations may restrict earlier use to protect pollinators and other non-target organisms. This is also the best window before grubs hatch and begin eating grass roots.
- Don’t soak your lawn from June through September, as this encourages female beetles to lay eggs. Instead, water deeply but more infrequently to support healthy roots and avoid consistently wet conditions. Also, maintain good lawn drainage to prevent standing water: try core aeration, level low spots, or install French drains.
- Dethatch your lawn every year (or as needed). Thatch is a hotspot for pests, and while some may be healthy for your lawn, thick thatch will attract grubs and other common lawn pests.
- Apply a fertilizer that suits your soil and grass type, and follow these mowing tips and tricks.
FAQ about eliminating grubs in your lawn
Will grubs go away on their own?
Sadly, no. Grubs burrow deep underground every winter, so they won’t actively damage your lawn for a few months. But the following spring, they’ll emerge in the soil again, just as hungry as ever.
Which grass types are most susceptible and least susceptible to grubs?
Choose warm-season grasses like Zoysiagrass or Bermudagrass for durability and resilience against grubs. Among cool-season lawns, tall fescue is the most resistant due to its tough, deep roots.
Some grasses, such as perennial ryegrass, Kentucky bluegrass, and creeping red fescue, are susceptible to grub attacks due to their dense or shallow root systems.
What happens if I don’t get rid of grubs?
Not treating grubs can cause more damage, weakening your lawn against other issues. Severe infestations might require reseeding or resodding, which costs more money and effort.
What should you do after treating for grubs?
For the best outcome:
- Avoid disturbing the treated area for a few days. This allows the product to take effect and protects children and pets from contact. Check the label for exact instructions.
- Repeat treatment as needed. Some grub control methods may require multiple applications. Again, check the product label on your chosen elimination method.
- After each application, water according to the label and monitor your lawn closely. Over time, you should see less damage and healthier grass.
Stop grubs in their tracks
Once grubs discover your lawn, they won’t let go unless you make them. They’ll come back every spring, destroying your lawn’s roots all over again. So, make this year the last one for the grubs in your yard. If nothing works, call a lawn care professional to help with your pesky grub problem.
Sources
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Main Photo Credit: JJ Gouin | Adobe Stock | License
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