Is your lawn turning brown? Grubs might be the cause. They eat grass roots, which means the grass can’t absorb water from the soil. If you want to save your lawn, you have to learn how to get rid of grubs.
Grubs (aka white grubs or lawn grubs) are the larvae of different types of scarab beetles, such as Japanese beetles, European chafers, or June bugs. They emerge from underground and feed in both spring and early fall.
When to look for grubs
For effective grub control, you have to understand the grub life cycle. Look out for damage from grubs in your lawn during spring and early fall. Here’s why.
In April or May, full-grown grubs come up to the surface after spending the cold winter months deep underground. It’s difficult to treat spring grubs, even with chemicals, because they’re so large and developed.
Those grubs soon grow into adult beetles and fly away from the soil mid-June, sometimes mid-May in hotter climates. They lay eggs during this time. If it’s Japanese beetles, they’ll also spend this time eating all your garden plants.
Then, in August or September, those eggs begin to hatch into a new wave of grubs. These grubs are very young and fragile, making this the perfect time for treatments. At the same time, all the adult beetles die out after living for around 40 days.
The second wave of grubs will feed on your lawn’s roots until around October when the weather starts to get cold. They go underground to spend the winter. Next spring, those grubs will come out again, and the cycle will repeat.
How to identify a grub problem
The first step to treating a grub problem is identifying it. Other problems such as drought stress, lawn diseases, and other pests cause brown patches that look similar to grub damage. So make sure grubs are what you’re dealing with before investing time and money in treatments.
What grubs look like
Even though there are thousands of species of grubs, they all look pretty much the same to the untrained eye:
- Size: ⅜ inch to 1 inch, depending on the species
- Shape: Worm-like bodies with three pairs of legs near the head; often curl into a C-shape when exposed
- Color: Milky white body with a brown head
Signs of grub damage
Grubs cause damage by eating the roots of your grass and sometimes small plants. Look out for these signs to let you know you have grubs:
- Yellowing grass that turns into brown patches
- Grass that pulls up out of the soil easily
- Grass that feels spongy when you walk on it
- More animals (such as birds, skunks, and raccoons) in your yard than normal and holes from pecking or digging
How to test your soil for grubs
The best way to be sure you’re dealing with grubs is to see them with your own eyes. But grubs live in the soil, so you have to do a little work before you can see them.
Grub soil test: 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 see them. You know you have an infestation if you see 10 or more grubs in the square foot of exposed soil.
Chemical grub control
Chemical insecticides are the most effective way to exterminate and prevent grubs in your lawn, but they have significant downsides.
These chemicals:
- Pollute groundwater, lakes, rivers, and other water sources
- Hurt bees and other pollinators
- Reduce populations of insects that prey on lawn pests like grubs, potentially making your grub problem worse in the future
- Can poison children or pets that come in contact with them
For these reasons, chemical pesticides should be a last resort. Only use them if your grub problem is severe, and you can’t get it under control with natural methods.
Curative pesticides for grubs
Curative pesticides are the ones you use when you already have grubs in your lawn. These chemicals will wipe out any grubs they touch, but they don’t have any residual effects on future grubs.
Best time of year for curative pesticides: Use these pesticides only when you’re sure you have active grubs in your lawn. They’ll be most effective on grubs present during August and September. Spring grubs are further along in their development and more resistant to pesticides.
Types of curative pesticides: For grubs, look for pesticides with the active ingredients carbaryl or trichlorfon.
Preventive pesticides for grubs
If you’ve had grubs before or suspect that you have, it’s a good idea to use preventive pesticides for the next few years to make sure they don’t come back. Preventive pesticides will have no effect on grubs currently living in your lawn.
Best time of year for preventive pesticides: For these pesticides to be effective, you have to apply them before grub infestation. Apply them in June or July to prevent grubs from hatching in fall.
Types of preventive pesticides: Look for grub pesticides with the residual chemicals imidacloprid, thiamethoxam, clothianidin, or chlorantraniliprole.
How to use dry vs. liquid pesticides for grubs
Curative and preventive pesticides both come in different forms, such as liquid sprays and dry granules or dusts. Here’s how to apply the different forms to your lawn for grubs
How to use dry pesticides for grubs:
- Step 1: Use a drop or broadcast spreader (a common lawn care tool you can find online or in garden supply stores).
- Step 2: Read the pesticide label to find out how much of the product you should put in your spreader and what adjustment you should set the spreader to.
- Step 3: Cover the entire lawn with the spreader. Do your best not to miss any spots.
- Step 4: After you spread the granules, water the lawn thoroughly so the pesticide soaks into the soil, where grubs live.
- Step 5: Leave the treated area alone until it dries. Check the product label to find out when the area will be safe for children and pets.
How to use liquid pesticides for grubs:
- Step 1: Use a hose sprayer for liquids. Some liquid pesticides already come in a hose spray bottle. If yours doesn’t, check the label for how much pesticide to put in the hose sprayer for the correct concentration.
- Step 2: Attach the sprayer to the end of any standard garden hose.
- Step 3: Spray the mixture of water and pesticide across your whole lawn. Try not to miss any spots or use so much that the liquid runs off into other areas.
5 natural ways to get rid of grubs in your lawn
If you want to avoid chemical insecticides (which we highly recommend), here are some organic methods you can try first.
The best time to try these methods is August through September, when newly hatched grubs are actively feeding on grass roots.
1. Beneficial nematodes
Beneficial nematodes are microscopic, living creatures that feed on grubs. Nematodes are a long-term solution because they reproduce on their own and continue feeding on grubs (and other pests) for years.
Because nematodes are alive, you have to introduce them to the lawn soon after you purchase them. They love moisture, so water the lawn before and after application, unless the ground is already wet from rain.
2. Milky spore
Milky spore is a bacterium that infects Japanese beetle grubs. It’s one of the oldest and most popular natural solutions to Japanese beetle grubs, but it requires patience. After you release the bacterium into your soil, it can take up to three years to work.
When you purchase milky spore, it comes as a powder. To apply, add a teaspoon of the powder to every 4 feet of your lawn. Water the lawn after applying. For best results, add milky spore to the lawn when the soil is between 60 and 70 degrees Fahrenheit.
Note: Milky spore doesn’t work on all grubs, only Japanese beetles. Distinguishing between different species of grubs is extremely difficult. Only use milky spore if you’ve had Japanese beetles before and you’re certain that’s the kind in your lawn now.
3. Neem oil
There are two types of neem oil: raw neem oil that contains the insecticide azadirachtin and clarified hydrophobic neem oil, which has most of the azadirachtin removed.
Clarified hydrophobic neem oil is usually the kind you’ll find in stores. You can use clarified hydrophobic neem oil to suffocate grubs in your soil.
Purchase a neem oil spray or mix one yourself with this recipe:
- Step 1: Mix ⅓ teaspoon of mild or natural soap (like Castile soap) into 1 quart of warm water.
- Step 2: Shake well.
- Step 3: Add 1 teaspoon neem oil to the mixture and shake well again.
Spray it on and around the brown patches in your lawn to suffocate grubs.
Warning: Neem oil can damage plants, so be careful not to get any on your garden plants. Grass is hardier and usually won’t suffer damage. Neem oil can harm beneficial insects, as well.
4. Lawn-aerating sandals
Yes, believe it or not, we mean the sandals that go on your feet. Lawn-aerating sandals are sandals with spikes on the bottom. They’re meant to poke holes in the soil for lawn aeration, but you can use them for grub control.
This method is quite simple. Wear the sandals and walk across your lawn a few times, concentrating on areas with brown patches. When the spikes poke into the soil, they should stab through at least some of the grubs in your lawn.
The sandal method may not solve large infestations. But if you have a small number of grubs in your lawn, aerating sandals could be worth a try.
5. Attract birds
Many birds feed on grubs (and adult beetles, too). A grub infestation alone is often enough to attract birds, but you can attract even more if you set up birdhouses, feeders, and baths around your yard.
The more birds you have hanging around, the more they’ll decimate your lawn’s grub population. Plus, a large number of predators can deter more adult beetles from moving into your lawn and laying eggs in the future.
3 natural ways to prevent grubs in your lawn
There are steps you can take to make your lawn less attractive to adult beetles when they’re laying eggs. If you can prevent them from laying eggs in your lawn, you won’t have grubs in the fall. Even if you have a few, there won’t be enough to cause significant damage.
The time to think about prevention is June through July, when adult beetles emerge from the soil and begin laying eggs.
1. Let your lawn dry out
Did you know your lawn can survive a few months of drought? But beetle eggs can’t. They need moisture to survive. If you stop watering your lawn during adult beetle season, you’ll see far fewer grubs come fall.
Stop watering your lawn beginning in June and on through September to exterminate grubs before they even have a chance to hatch. Your lawn will go dormant during this time, which means it will turn brown. But it should spring back to its normal self when you resume watering.
2. Dethatch every year
Thatch, the layer of grass clippings and other debris that builds up in your lawn over time, is a hotspot for pests, including grubs. Some thatch is healthy for your lawn, but too thick of a layer will attract grubs and other common lawn pests.
Dethatching your lawn every year will make it less attractive as a breeding ground. A lawn with a healthy thatch layer attracts fewer grubs and other pests than one with excessive thatch.
3. Proper lawn care
A healthy lawn also can prevent grubs. Adult beetles have a harder time laying their eggs when thick, tall grass blocks access to the soil.
How can you keep your lawn lush and healthy? Here are some basic proper lawn care practices:
- Mow your lawn to the right height for your grass type. Too long or too short, and you could affect the grass’s health.
- Fertilize your lawn on a regular schedule to boost healthy growth.
- Don’t overwater your lawn. Overwatering is even worse than underwatering in most cases. Too much water attracts pests and leads to weak roots, which are more susceptible to grub damage.
When your grass is healthy, it develops a deeper, stronger root system. That way, your lawn can resist damage from grubs even if you aren’t successful at preventing them.
These tips might seem like a lot of work, but you aren’t alone on your journey to a healthier lawn. Count on Lawn Love’s local lawn care pros to help with all your maintenance needs.
FAQ about grubs
Sort of, but not really. 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.
Warm-season grasses resist grub damage better than cool-season grasses. Tall fescue is the best grass type for resisting grubs.
The best time to exterminate existing grubs is August or September, when the grubs are young, vulnerable, and actively feeding on roots. Grubs that appear in spring are older and tougher, so they’re harder to exterminate.
The best time for preventive grub treatments is June or July when adult beetles have started laying eggs and none have hatched yet.
You can tell if you have grubs by actually seeing them. Dig up a portion of your soil in the damaged area of the lawn and you should find live grubs, if that’s your problem. If you don’t see any grubs, you may have a case of lawn fungus instead.
Stop grubs now, thank yourself later
Once grubs get their tiny hands on your lawn, they won’t let go unless you make them. They’ll keep coming back every spring, destroying your lawn’s root system all over again with each new generation.
Make this year the last one for grubs in your lawn. Take steps as soon as possible to exterminate and prevent grubs, and you’ll save yourself a headache next year…and the next…and the next…and the next…
Are grubs still turning your lawn brown after you’ve tried everything? That means it’s time to bring in a pest control professional.
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