When To Treat For Grubs – Protect Your Lawn

Grubs refer to soft-bodied larvae of different beetle species, such as Japanese beetles and European chafers. They are identifiable by their C-shaped form, white or tan coloring, and brownish head. These pests feed on the roots of grass, causing substantial damage and leading to patches of dead grass. They have a one-year life cycle and usually overwinter as mature larvae in the soil, laying eggs in the spring. Grubs can significantly harm a healthy lawn, so it is crucial to detect their presence and take preventive measures using grub control products.

When To Treat For Grubs To Protect Your Lawn

The best time to treat for grubs is Late Summer and Early Fall, this will vary depending on your climate, but generally around July-Early September is the best time to treat for grubs! During this period grubs are younger and more susceptible to grub treatments compared to during the Summer or later.

when to treat for grubs

You can also treat with a preventative grub treatment in April or May to help prevent grubs in Fall.

Factors to Determine When to Treat For Grubs

Timing is essential when it comes to applying preventative treatment for grubs. To effectively manage grub infestations, lawn owners should consider several key factors when determining the best time to treat.

Firstly, it is important to monitor soil temperatures. Grub activity tends to increase when the soil temperature is between 60-80°F. Therefore, preventative treatment for grubs should be applied during late spring or early summer right before the soil reaches this range so you’re prepared.

soil temperature for grubs

Also, understanding the life cycle of the grub is essential in deciding when to treat. Grubs have one generation per year and develop slowly in the soil. They are often most susceptible to treatment when they are in the early larval stage. Applying treatment during this phase ensures that the chemical is most effective in controlling the population and preventing further damage to turf.

Lastly, the presence of adult beetles is an important factor to consider. Adult beetles will typically feed on tree leaves and are often seen in early to mid-summer. This presence is a good indicator that the grubs will soon hatch and start to feed on grass roots, eventually leading to patches of dead grass.

Types of Grubs

Grubs are notorious lawn pests that can cause severe damage to your turfgrass. They are the larvae of various beetles, including Japanese beetles, European chafers, and Oriental beetles.

treating grubs

The most common grub species found in North America are Japanese beetle grubs and European chafer grubs. These grubs have different life cycles, which affect the timing of when you can control them.

Japanese Beetle Grubs

Japanese beetle grubs have a one-year life cycle, laying eggs in mid-summer, and hatching in about two weeks. They feed on grass roots until they become mature grubs in the fall, overwintering deep in the soil, and emerging as adult beetles the following summer.

European Chafer Grubs

European chafer grubs have a two-year life cycle, laying eggs in mid-summer in the first year, and hatching within two to three weeks.

The grubs feed on grass roots until they become mature in the fall, overwintering deep in the soil. In the second year, the grubs resume feeding on roots until they pupate in May and emerge as adult chafer beetles in late June and early July.

Signs of Grub Damage

Grubs are lawn pests that can cause considerable damage to the roots of grass. It’s crucial to identify the signs of grub damage as early as possible to prevent an infestation and ensure healthy turf. Some indications of grub activity include dead patches of grass that pull away from the soil easily, or adult beetles that are active in the area. By recognizing these signs early, you can take preventive action to control grubs before they cause severe damage. 

Brown Patches In Your Lawn

Brown patches in a lawn can be a sign of grub damage. Grubs are white, C-shaped larvae that live in the soil and feed on the roots of grass. Tim Schimpf, the owner of Herbi-Systems, recommends “digging up a square foot of turf to examine the roots of grass for signs of grub damage. If the roots are chewed or missing, it may indicate a grub infestation.”.

brown spots from grubs

Curative treatments include the use of grub control products, which contain pesticides that kill grubs on contact. Preventive treatments can include the use of beneficial nematodes, which are microscopic organisms that infect and kill grubs. Because grubs are a big part of a moles diet, you might also notice mole damage in your lawn which will add to the yellowing of your lawn as well as the digging of holes. Check out our guide on some signs of moles in your lawn! If you know you have moles then you can take a look at some effective mole traps!

To maintain a healthy turf, it’s important to address grub infestations promptly. Preventive applications of organic matter can improve soil health and encourage the growth of beneficial insects that prey on grubs, while curative applications of preventive chemicals can keep grub populations under control. With regular monitoring and treatment, brown patches caused by grub damage can be easily avoided.

Dead Patches of Grass and Turf

Dead patches of grass and turf are a common symptom of grub damage. These patches may vary in size, ranging from several inches to several feet. Often, dead patches will be circular or oblong, indicating the presence of grubs feeding below the soil surface. The grubs eat the roots of the grass, causing it to die and turn brown. Dead patches of grass may also appear to be sunken in, due to the lack of grass roots.

Grub Activity in the Soil

Grubs are common lawn pests that can cause serious damage to the roots of grass, resulting in brown patches and dead grass. Without proper treatment, grub activity can quickly spread and infest an entire lawn. To identify the presence of grubs, check the soil surface temperatures. As grubs thrive in warm soil, a temperature above 70°F is a clear indicator of their activity.

How to Tell if You Have an Active Infestation or Just Remnants from Past Years?

Grubs can be a serious threat to the health of your lawn. However, it’s essential to know if you have an active infestation or just remnants from past years before deciding to take action. Here are some tips to identify an active infestation versus remnants.

Firstly, check for dead patches of grass or spongy areas in your lawn. These are clear signs that your turfgrass roots are being attacked by grubs. If you have a history of grub activity, this may signal a recurring issue. However, if you’ve never experienced these problems before, it’s likely an active infestation.

signs of active grub infestation

Another sign to look out for is the presence of six or more grubs in a damaged section of the lawn. This can confirm an active population that may need treatment. Keep in mind that grubs come in different species, and each can have varying levels of damage and activity.

Lastly, keep an eye out for birds, skunks, or raccoons tearing up the lawn. These critters love dining on tender grubs, and their presence can signify an active infestation.

Final Thoughts On When To Treat For Grubs

Treating for grubs at the right time of the year will make all the difference in whether the grub treatment was successful or not. It can range depending on your region, but generally speaking, you want to put down preventative grub control in the Spring and then traditional grub control treatments in Late Summer or Late Fall.

I hope this guide on when to treat for grubs was helpful in protecting your lawn against these pests!



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