Lawn grubs are the larval stage of adult insects like Japanese beetles, June beetles, or European chafers. These lawn pests are small (though up to 1"), white, C-shaped creatures that live just below the soil surface. They feed on organic matter, primarily grass roots, and eventually cause brown or yellow patches of dead spots in your lawn.

The telltale sign of grub damage is dead patches of grass that may feel spongy or pull up easily like loose carpet. Birds, raccoons, or skunks may have noticed the signs of grub activity before you do and in their pursuit of a snack, they'll add to the visible damage by digging into your lawn. A healthy lawn can handle about five grubs per square foot, but you don't want it getting out of hand. The best way to get a grip on grub activity is to use a chemical control in the autumn. This is when grub feeding is at a high which makes them much more susceptible to treatment.

Preventative vs. Curative Insecticides for Grubs

When it comes to lawn grub control, you’ll have two main options: preventative and curative insecticides.

• Preventative Insecticides: These are applied before grubs hatch, typically in late spring or early summer. They kill young grubs before extensive feeding begins. Common active ingredients include imidacloprid and chlorantraniliprole. Preventative treatments are highly effective when timed correctly, before adult beetles lay new eggs. Preventative products won’t help much if the white grubs are already actively feeding.
• Curative Insecticides: Designed for use when you already have an active grub problem, curative products work by killing mature grubs in the fall. Products with active ingredients like trichlorfon and carbaryl are best suited for curative applications. Keep in mind, curative treatments require immediate action once you notice the signs of damage.

Do natural treatments work?

Natural grub treatments like biological controls can be effective under the right conditions, i.e. sooner than later. Beneficial nematodes, for example, are microscopic worms that attack grubs. Milky spore is a bacterium that continues to kill Japanese beetle grubs over time. Aside from these grub killers, an easy, natural preventative trick is to over-seed in the late fall or early spring as it's harder for grubs to take hold of a lush lawn.

Keep in mind that natural solutions will take longer to get control of grubs and you'll risk more lawn damage the more time it takes.

Why to Control Grubs in the Fall

• Treatment is most effective. Combined with autumn rain, granular products will slowly seep into the soil, drawing out treatments and making them more effective.
• Less damage accumulates if you treat grubs before winter. Even moderate damage can make your lawn more vulnerable to weeds, disease, or drought stress.
• Fall treatments target larger grubs. This is when their appetites are highest and before they mature and produce more eggs.
• Prepares your lawn for winter dormancy, preventing weak spots where grubs have been feeding. You may want to over-seed the lawn to overcompensate for an existing grub population.

Hire a Pro or DIY

Treatment of a grub infestation depends how severe it is. If you have a minor problem and are willing to invest time in applying products correctly, DIY methods can be effective. This is especially true for preventative measures like general lawn care of introducing beneficial insects. If you apply store-bought chemical lawn grub treatments, expect it to take 10-14 days after application for the grubs to die and longer still to see an improvement.

Lawn pest professionals obviously have more experience but also they often have access to stronger, more effective products. This would be your best course of action against severe damage. If you're facing an active grub infestation, hiring a pro is your best bet to get you back on track for beautiful grass.