Pro Tips

How to Control Lawn Grubs

It isn’t just weeds and drought that cause damage to your lawn—grubs can be a landscape challenge as well. Fortunately, these are some effective options for controlling them.

Lawn Grubs 101

Also known as white grubs, lawn grubs have small white bodies that curl up in a C-shape if disturbed. They are the larvae of many different species of scarab beetles, including green June beetles, Japanese beetles, Oriental beetles, and chafer beetles.

For most of the year, lawn grubs are active a few inches below the soil. In the winter, they head down to a depth of about 4 to 8”.

While grubs damage the lawn, the insects eat away at the foliage and flowers

Grubs feed on grass roots, causing damage to your lawn. After developing into beetles, they continue to feed on and damage foliage and flowers. Most scarab beetles have a one-year life cycle. Eggs laid by the female beetles in the lawn hatch over the summer, and the young grubs feed into the fall, when they do most of the damage. They have a period of inactivity over the winter but resume feeding in the spring.

SHOP LAWN AND GARDEN CARE

Identify If You Have Grubs

Person checking the soil underneath turf

The presence of grubs can cause a few different types of damage to your lawn. In late spring and fall, you might see randomly shaped patches of dead grass. In early spring the following year, brown patches that don’t go green may indicate previous fall feeding.

Animals that come to feed on the grubs (like moles, birds, skunks, and raccoons) can also tear into and damage your lawn. Additionally, you might find turf that has a spongy feel and lifts away easily to reveal damaged or destroyed roots.

There are other lawn conditions that can have these symptoms, so you have to confirm the presence of grubs and see if you need pest control by directly checking the soil.

Make 3” deep cuts from 6-12” long on three sides of a grass patch.
Peel back the turf and count the grubs if you see any.
Check multiple spots to make an estimate of grubs per square foot.
Replace the turf when you are finished checking.

Most healthy lawns can sustain a per-square-foot rate of up to five grubs without issue. Six or more grubs per square foot, however, often create damaged areas and require treatment, especially if they are attracting animal activity. If you calculate a rate of 10 or more, then your lawn likely needs thorough treatment as it will have noticeable damage.

Pro Tip

In the summer, watch for beetles flying around your and your neighbour’s lawns: it may signal a grub problem in the fall and spring. Grub activity is more common on unshaded and well-watered lawns, as it increases the chances of egg-laying and grub development.

Manage Grubs by Taking Good Care of Your Lawn

The main method of managing lawn grubs is to maintain a healthy lawn. Thick and healthy grass discourages grubs and beetles while deep and strong roots are better able to tolerate damage.

See our 7 simple rules for regular lawn maintenance to learn more about good lawn care.

Use Insecticides

The next line of defence against grubs are products called insecticides. Due to active ingredients like trichlorfon, these products are capable of killing grubs at any stage of development.

If you had grub problems a year before and expect it to be an issue again, then you can try a preventative insecticide that contains chlorantraniliprole or imidacloprid. Preventative products kill the grubs as they hatch, avoiding the subsequent damage they could cause.

The effectiveness of insecticide differs based on application timing and active chemical. Follow all of the package recommendations and pay special attention to the type of insects it will kill. You don’t want to exterminate species like mantis and dragonflies, which can be beneficial.

Note of Caution

When you use a lawn care product, always read and follow the package directions about clothing, protective equipment, safety precautions, and proper application procedures.

Pro Tip

Mow before applying insecticide for grub worms to help the chemical quickly reach the soil. Consider dethatching and aerating your lawn as well using gardening tools such as a lawn aerator or cultivator.

Opt for Grub Insecticide Alternatives

For treatment options that don’t use insecticides, here are some alternatives:

Natural Predators

Natural predators can keep grub worm populations in check, and there are many of them. Try to encourage ground beetles, ants, wasps, and birds to visit your yard. Simply choose from these 10 plants and flowers to attract birds and pollinators.

Dormant Grass

Consider letting your grass go dormant in the summer so that the dry soil is less attractive for beetles to lay their eggs in.

Repair Damage from Grubs

After you have found a method that works to control grubs in your lawn, it’s time to repair the damage. Usually, once you clean up the dead material and water the area, it will recover with some proper care.

Selecting Grub-Tolerant Grass Species

If you’re always fending off grubs, then planting a grub-tolerant grass species might be a good idea. No grass is totally grub-resistant, but varieties that grow deep root systems can tolerate both grub damage and drought better.

Drought-tolerant grass is also a good choice as it does better in the dry conditions that grubs don’t like. Warm-season varieties are a better option than cool-season grasses but, of the cool-season grasses, tall fescue is the most tolerant of grubs.

How to Control Lawn Grubs

Lawn Grubs 101

While grubs damage the lawn, the insects eat away at the foliage and flowers

Identify If You Have Grubs

Pro Tip

Manage Grubs by Taking Good Care of Your Lawn

Use Insecticides

Note of Caution

Pro Tip

Opt for Grub Insecticide Alternatives

Repair Damage from Grubs

Selecting Grub-Tolerant Grass Species

Gazebos and pergolas

Outdoor power equipment

Barbecues and smokers

How to Control Lawn Grubs

Lawn Grubs 101

While grubs damage the lawn, the insects eat away at the foliage and flowers

Identify If You Have Grubs

Pro Tip

Manage Grubs by Taking Good Care of Your Lawn

Use Insecticides

Note of Caution

Pro Tip

Opt for Grub Insecticide Alternatives

Repair Damage from Grubs

Selecting Grub-Tolerant Grass Species

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