When to Apply Grub Control [Best Time to Treat Your Lawn]

Grub damage starts to become evident in around May when there’s increased activity following the feeding program that you started in early spring. It is important to know when to apply grub control in order to prevent damage to your grass.

The best time to apply grub control is between early spring and late summer when there’s increased grub worm activity in your lawn. For grub preventers, apply between June and July just before they hatch while for grub killers, apply the treatment from spring when you see signs of grub damage in grass.

June bugs, billbugs, and European chafers usually lay their eggs in lawns and gardens. As soon as they hatch, they develop into grubworms and start eating the grass roots throughout the warm seasons.

You’ll notice signs of dead patches of grass any time from early spring to mid summer when the damage stops due to the grubs having developed into pupae and adults.

So, throughout this life cycle of Japanese beetles and European chafers, what is the best time to treat for grubs with a preventer or a killer?

What’s the Best Time to Apply Grub Control

The best time to apply grub control depends on whether you’re preventing them or killing the ones already damaging your lawn. It is usually best to put down grub preventers in June and July just when the grubs are about to hatch. This will provide the best preventative control of grubs for the next season.

If you want to stop grub damage immediately, the best time to apply grub killer insecticide in your lawn is as soon as you see signs of damage. This is usually any time between early spring to early August when the grub worms are most active eating and damaging grass in your lawn.

But, when is it too early to apply grub control?

When treating your lawn to prevent grub damage for the next season, it would be too early to apply grub preventer on your turf in early spring.

The pesticide will easily disintegrate into the soil and lose its potency by the time the grubs hatch in July through August.

According to the Colorado State University Extension, “insecticides are best used in ways that allow them to be in high concentration in the root zone at the same time eggs are hatching and young white grubs are present.”

When timing is done right, you’ll be able to control about 80 percent of the grubworm infestation in the next season.

For the grub killers, you can stop lawn damage almost immediately especially if you follow the right application guidelines on the label of the pesticide.

What to Do after Putting Down Grub Control Pesticide

You want to get the best effects after applying the pesticide on your lawn. Here are a few tips on what to do after the application:

• Water your lawn immediately after putting down grub control: Most grub killers and preventers come as granular formulations. For them to be effective, water your lawn to at least 1-inch.
• Monitor your lawn for grub worm activity after treating it. After applying a grub killer, you expect eradication to happen within a few days to a week. If the damage continues, it is likely the grub treatment was not enough or did not work.

Pro tip: Some grub control pesticides such as Scotts GrubEX provide long-term control and can be applied almost any time of the season. It can kill adult beetles and reduce their population in your yard.

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Do You Need to Apply Grub Control Every Year?

Did you find grubs in your lawn last spring? Then you may need to apply a grub preventer for lawns.

You do not need to apply grub control every year successively unless you see grub damage. If you’ve been treating your lawn with a grub preventer and killer for a few years in a row, it may be time to stop until you see the signs of grubs and European chafers again.

Grub preventers help control grubs for every next season. You cannot apply a grub preventer to kill grubs that are already damaging your lawn. If you’re applying a grub preventer, it will not get rid of grubs that may be present in your lawn from mid-October through the middle of May.

For that, you need to apply a grub killer such as GrubEx.

When to Apply Grub Control?

You need to apply the insecticide between May and July to prevent infestation for the next season by killing and harming the development of the next generation of grub worms in your lawn.

In healthy turfs, a few grubs should not be a problem and you may not need to apply insecticide every other year. You only need to start a grub control treatment when you see signs of damage.

If you feed your lawn properly, your grass can support about 5 grubs per square foot of turf without any visible damage. Your lawn will still look green and healthy because the damage from their feeding activity will be very minimal.

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Alternatively, a homemade solution for controlling grubs in a lawn is to use Dawn dish soap. It may not completely eliminate grubs, but it can assist in managing light infestations.

You can also use Milky Spore to control bugs and worms in your lawn, but that comes with pros and cons.

How Often Should You Apply Grub Control?

Grub treatments are effective when applied at the right time. In some cases, you may need to apply the pesticide two or three seasons in a row to completely eradicate grubs in your lawn.

In most cases though, you’ll only need to apply grub control twice in a season – the first one being a grub killer when you see signs of infestation and the second one being a grub preventer around June and July to stop their cycle.

What to Look for in Grub Preventers

Most homeowners mean to kill grubs when they see signs of infestation. However, the best way to control their damage for the long-term is by putting down a preventer.

A good grub control preventer will contain any one of these active ingredients:

• Imidacloprid
• Chlorantraniliprole
• Thiamethoxam
• Clothianidin

The reason why you want to look for these ingredients is that they are very good at killing grubs at a tender age, usually as soon as they hatch.

Ingredients that DO NOT Work On Lawn Grubs

There are a few active ingredients in grub control products that simply don’t work. As an example, products that only contain lambda-cyhalothrin, gamma-cyhalothrin, bifenthrin, deltamethrin, cyfluthrin or permethrin won’t be effective in killing grubs.

Adding to this, there are a few curative products that are only effective in eliminating grubs when applied at the right time. For example, carbaryl, trichlorfon or zeta-cypermethrin are billed as curative grub control products and only work when applied in late summer and fall.

Read the product label carefully to determine the active ingredients and follow the manufacturer’s instructions on application procedures.

Types of Grub Control

There are two types of grub control products – preventive chemicals and curative chemicals, and here’s the difference between the two to help you make the right choice.

Preventive Chemicals

Preventive chemicals are those that prevent pests from becoming established before the situation spirals out of control. If applied properly, preventive herbicides can be very effective against the growth of grubs.

Products	Ingredients	When to Apply?
Bonide	imidacloprid	Apply the product every 8 weeks during the growing season
Tandem	Lambda-cyhalothrin and thiamethoxam	June or July and watered-in with 0.5 inches of irrigation
Acceleron	Clothianidin	June or July and watered-in with 0.5 inches of irrigation

Curative Chemicals

Curative chemicals kill grubs that are already in the soil at the time of application. They work by working their way down through the soil and kill grubs upon contact.

Products	Ingredients	When to Apply?
DuoCide	Bifenthrin and carbaryl	Kills 20-80% of grubs when applied in September or 20-55% when applied in late October
Trichlorfon	Trichlorfon	Kills 20-80% of grubs when applied in September or 20-55% when applied in late October

Can Scotts Grubex Be Applied in the Fall?

The best time to apply GrubEx is early spring through mid-summer when grub activity in lawns in heightened. Fall might not be a very good time to put down grub control.

As temperatures continue to drop with winter approaching, grubs dig down approximately 4-8 inches into the soil and lay there until temperatures start to rise again.

You may not get much success controlling lawn grubs and European chafers if you apply GrubEx in October and November, or the duration of fall because it might be too late to treat for grubs.

How & When To Treat Grub Worms In the Lawn

When to Apply GrubEx

The best time to apply GrubEx is during the spring or early summer. Applying this formula will kill grubs as they develop. As a precaution against future invasions of grubs, you can apply Scotts® GrubEx®₁ Season Long Grub Killer annually, which stops and prevents grubs with a single application.

You can apply GrubEx before the rain, which will water in and activate the product. With regard to application, you can apply GrubEx with a spreader, and then water it thoroughly to activate it or wait for rainfall.

Grubs Damage Photos

Tips Before Applying Grub Control

Here are a few tips before applying grub control to help you get get the job done right.

• First things first – make sure that you indeed have a grub problem before resorting to any treatment methods. There are several telltale signs to let you know that you have grubs strolling in your lawn such as when you actually see grubs, dead patches, spongy spots, hovering moths, and/or more birds, raccoons, armadillos, skunks, or moles coming to pay a visit
• Since each product varies, it’s important to check the product label to determine the active ingredient. Doing this will also let you whether the product is a preventive treatment or a curative so you can apply it at the right time for best results
• Next, do not buy and use products that only contain certain ingredients such as lambda-cyhalothrin, gamma-cyhalothrin, bifenthrin, deltamethrin, cyfluthrin or permethrin because they do not on their own work towards solving the grub damage to lawn or grub damage to garden problem. Follow the instructions like dosage and best time to apply listed in the respective product label
• Remember, these ar chemicals you’re dealing with so make sure you wear protective gear such as safety gloves, safety glasses, a long-sleeved shirt, and long-sleeved pant
• After spreading the grub control product, irrigate your lawn with at least 0.5 inches of water. Rainfall or irrigation will activate the grub killer and make the application more effective
• If you have kids or pets that you feel won’t stay off the lawn, consider using a natural grub killer such as nematodes for grubs.

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FAQs

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Final Thoughts

If you want to get rid of grubs, it’s important to apply a grub control product at the right time. There are two types of treatments for grubs – preventive and curative treatments, where the former should be applied before the invasion of grubs and the latter if your lawn is already plagued with grubs.

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References

• K-State Extension: Grub Control: How to get rid of grubs in the lawn
• Colorado State University Extension: Billbugs and White Grubs: Control in Home Lawns – 5.516
• The Connecticut Agricultural Experiment Station: Managing White Grubs in Home Lawns