Grubs are the reason a healthy lawn suddenly develops brown patches that peel back like loose carpet, and why skunks and birds start tearing it up overnight. But most lawns have a few grubs and are perfectly fine, so the first job in learning how to get rid of grubs is finding out whether you actually have a problem worth treating. Reaching for a chemical because you dug up one grub is how people spend money and harm the soil for nothing.
Quick answer: To get rid of grubs, first confirm you have enough to matter: cut a 12-inch square of turf, peel it back, and count the white C-shaped grubs in the top few inches of soil. Treat only if you find more than about 5 to 10 per square foot, or 5 to 7 on stressed turf. Apply a preventive product in spring, April to May, before eggs hatch, or a curative product in July to August while grubs are small and feeding near the surface, and water it in immediately. Beneficial nematodes are an effective non-chemical option applied while grubs are young.
Key takeaways
- A few grubs are normal. Nearly every lawn has some. One or two is not a problem and needs no treatment.
- Confirm the count first. Cut and peel a 12-inch square and count. The threshold is roughly 5 to 10 per square foot.
- Grubs are white and C-shaped with a brown head and six legs, sitting in the top 1 to 3 inches of soil.
- Timing decides which product. Preventive in spring before hatch; curative in mid to late summer while grubs are small.
- Always water it in. Granular products must be watered into the lawn immediately to reach the grubs.
- Nematodes are the biological option, applied while grubs are young, and they need a moist lawn.
Do you actually have a grub problem?
This is the whole first half of the job, and skipping it is the most common and expensive mistake. Grubs are the larvae of beetles such as Japanese beetles, chafers, and June beetles, and a small population is a normal part of a living lawn. The soil is supposed to have some.
The signs that point to a real infestation are specific:
- Irregular brown patches that appear in late summer and do not green up with water, because the roots are gone.
- Turf that lifts like a loose rug. Clemson University Extension notes the turf can be lifted from the soil because the grubs have eaten the grass roots. If you can roll it back by hand, that is the tell.
- Spongy soil underfoot in the affected areas.
- Animals digging. Skunks, raccoons, armadillos, and birds tearing up the lawn at night are hunting the grubs, and the digging often does more visible damage than the grubs themselves.
The square-foot test
This settles it in ten minutes. Clemson’s method: cut three sides of a 12-inch square with a knife or spade, peel the turf back like a flap, and carefully inspect the root zone and the upper 1 to 3 inches of soil, counting the grubs. Do this in several spots around the lawn and average them, because grubs cluster.
The grubs you are looking for are dirty white, soft-bodied, with a brown head and three pairs of legs, and they curl into a distinctive C shape when you lift them out. Then compare your count to the threshold below and fold the turf flap back down, firming and watering it if you found nothing.
The treatment threshold
The number of grubs a lawn tolerates depends on how healthy it is, and the figures come straight from extension research.
| Situation | Grubs per square foot before treating |
|---|---|
| Healthy, well-watered turf (Japanese beetle) | 6 to 8 |
| Vigorous, well-managed turf (masked chafer) | up to 20 |
| Stressed, thin, or dry turf | 5 to 7 |
The lesson is that a strong lawn shrugs off far more grubs than a weak one. A vigorous lawn with deep roots can carry 20 grubs per square foot with no visible damage, while a stressed lawn shows harm at a third of that. This is why the single best grub defence is a healthy lawn, and why fixing the underlying vigour matters as much as killing the grubs. If you find one or two grubs in your square, you do not have a problem and should not treat.
When to treat, and with what
Timing is not a detail here, it is the whole strategy, because grubs are only vulnerable at certain stages. Get the timing wrong and even the right product does little.
- Preventive products, spring. Clemson advises applying preventative applications in the spring, April through May. These sit in the soil and kill the young grubs as the eggs hatch. This is the approach for a lawn that had grubs last year, and it is the more reliable of the two.
- Curative products, mid to late summer. Apply during July or August, while the newly hatched grubs are small and feeding near the surface. Once grubs are large and have moved deeper in autumn, curative products work poorly, so a late-season panic treatment often fails.
- Beneficial nematodes, while grubs are young. Clemson lists Heterorhabditis bacteriophora nematodes, which seek out grubs and enter through natural openings in the body. They work best on small grubs, have a short shelf life, and must be applied within the season bought.
The single most important application rule, whichever product you use: granular products must be watered into the lawn immediately after application, because the active ingredient has to move down through the thatch and soil to reach the grubs. A grub product left dry on the surface does nothing. For applying liquid treatments and nematodes evenly, the best insecticide sprayers give consistent coverage, and for the chemical options the best lawn grub killers cover both preventive and curative products.
The nematode route, step by step
Beneficial nematodes are the option for anyone who would rather not put insecticide on the lawn, and they genuinely work when applied correctly. They are microscopic worms that hunt grubs and are harmless to people, pets, and earthworms.
- Buy fresh and use immediately. Nematodes are living organisms with a short shelf life. Check the packing date and apply within the season.
- Apply while grubs are small, typically late summer for a curative approach, matching the same window as curative chemicals.
- Water the lawn first. Nematodes need a moist soil to move through, so irrigate before applying.
- Mix and spray in the evening or on an overcast day. UV light and heat kill nematodes, so never apply in bright midday sun.
- Use a sprayer with the filter removed or a coarse setting, since fine filters strain the nematodes out.
- Water again after applying to wash them down into the root zone where the grubs are.
- Keep the lawn moist for two weeks so the nematodes survive and spread.
Prevention: a healthy lawn is the real defence
The threshold table makes the point that a vigorous lawn tolerates several times more grubs than a weak one, so everything that builds lawn health also builds grub resistance. This is the same set of practices that runs through the whole lawn care series.
- Mow high. Longer grass has deeper roots that survive grub feeding better, covered in how to mow a lawn.
- Water deeply and infrequently. Deep roots reach below where grubs feed. See how to water a lawn.
- Fix compaction and thatch. Both stress the lawn and make grub damage worse, addressed in how to aerate a lawn and how to dethatch a lawn.
- Overseed thin areas to keep the turf dense, using how to overseed a lawn.
One more prevention note: adult beetles are drawn to lay eggs in lush, well-watered lawns during their summer flight, so overwatering in midsummer can actually invite the next generation. And beware treating for grubs that are not there, which harms the beneficial insects and earthworms that keep soil healthy.
Common grub-control mistakes
- Treating without counting. Finding one grub and reaching for chemicals wastes money and harms the soil.
- Treating at the wrong time. Curative products applied to large autumn grubs barely work.
- Not watering the product in. Granules left dry on the surface never reach the grubs.
- Using old nematodes, or applying them in bright sun, both of which kill them before they work.
- Assuming all lawn damage is grubs. Drought, disease, and dog urine cause brown patches too. The turf-lift test is what confirms grubs.
- Ignoring lawn health. A stressed lawn shows grub damage at a fraction of the count a healthy one shrugs off.
Frequently asked questions
How do you know if your lawn has grubs?
Look for brown patches that do not green up with water, turf that lifts like loose carpet, spongy ground, and animals digging at night. Confirm by cutting a 12-inch square, peeling it back, and counting the white C-shaped grubs in the top few inches of soil. More than about 5 to 10 per square foot warrants treatment.
How many grubs are too many?
Roughly 5 to 10 per square foot is the usual threshold, but it depends on lawn health. A vigorous, well-managed lawn can tolerate up to 20 per square foot with no visible damage, while a stressed or thin lawn shows harm at 5 to 7. Finding one or two grubs is normal and needs no treatment.
When is the best time to treat for grubs?
Preventive products go down in spring, April to May, before the eggs hatch, and are the most reliable if you had grubs last year. Curative products are applied in July or August while the young grubs are small and feeding near the surface. Late autumn treatments on large grubs work poorly.
Do beneficial nematodes really work on grubs?
Yes, when applied correctly. Heterorhabditis bacteriophora nematodes seek out grubs and kill them, and are harmless to people, pets, and earthworms. They work best on small grubs, need a moist lawn and application out of direct sun, and have a short shelf life, so buy fresh and use them within the season.
Why do I need to water in grub killer?
Because the active ingredient has to move down through the thatch and soil to reach the grubs feeding on the roots. Granular grub products must be watered in immediately after application, or they simply sit on the surface and do nothing. Nematodes also need watering in to wash them down to the root zone.
Will grubs go away on their own?
A small population is normal and self-limiting, and a healthy lawn simply outgrows the damage. A genuine infestation above the threshold will keep damaging the lawn and attract digging animals until treated. The grubs themselves pupate into beetles and leave, but they lay the next generation first, so a real problem recurs.
Final thoughts
Getting rid of grubs starts with proving you have them: cut a square, peel it back, and count, treating only above about 5 to 10 per square foot. Then match the product to the season, preventive in spring or curative in mid summer, water it in, and consider nematodes if you would rather skip the chemicals. Above all, build a vigorous lawn, because a healthy one tolerates several times more grubs than a weak one and rarely needs treating at all. If your count is over the line, the best lawn grub killers are where to start.