How to Control Grubs

Get ahead of leafy chewers by attacking them at the larval stage.
Related To:
Japanese Beetles Crawling on a Leaf

Japanese Beetles Crawling on a Leaf

Grubs are the larval form of most beetles and in particular the Japanese beetle.

Grubs are the larval form of most beetles and in particular the Japanese beetle.

"Controlling all sorts of critters that spend most, if not all, of their lives underground can be a real challenge, especially if you can't see them," says master gardener Paul James. "And that's especially true of grubs, the larvae form of most beetles and in particular the Japanese beetle. The adult stage of these beetles can do a tremendous amount of damage to your plants, especially roses."

To help get ahead of the adult beetles, you can begin by working on the grubs. Most grubs begin life in early summer as eggs laid four inches underground by their mother. Early the following spring, the larvae begin an upward migration seeking food, primarily in the form of various plant roots. The secret to controlling larvae is to know the timetable of their life cycle and to take appropriate steps to control them.

One of the best ways to control them is by using a white powder known as diatomaceous earth, or simply DE. DE is a nontoxic, organic concoction made of the fossilized remains of tiny one-celled marine animals called diatoms. Chemically, it's almost pure silicone dioxide. To humans, DE feels really soft to the touch, but to grubs it's like razor wire that literally shreds them as they touch it.

Sprinkle DE on the soil at the rate of about 1/2 cup of powder per square foot and mix it into the soil to a depth of about six inches. DE can cause respiratory problems, so wear a mask and work with it on a nonwindy day. DE can also harm beneficial insects, such as earthworms, so use only where grubs are a problem.

"You should apply diatomaceous earth each spring in the soil to control grubs," Paul recommends, "and you can also sprinkle it around the base of plants during the summer months to control just about anything that crawls — from Mexican bean beetles to squash bugs." But make sure to buy the horticultural grade; there's another kind available for swimming pool filters, but it has been treated and won't work on grubs.

Keep Reading

Next Up

Garden Plants and Flowers

Learn how to discover which plants underscore and help define a specific garden design style.

Choosing Colors and Textures for Your Garden

Learn how to change the look and feel of your garden with this guide.

Garden Design: Connect Your Indoor and Outdoor Spaces

Let your indoor space inspire your landscape design plans.

How to Distress Furniture

What's old is chic again. Follow these step-by-instructions for achieving a distressed look on furniture.

How to Remove Wallpaper

How do you remove the wallpaper without damaging the wall – or yourself? Use these tips to help you decide which option will work best.

How to Freeze Apples

Save that apple bounty for the months ahead.

How to Kill Mold

Killing mold is a dirty job, but the right tools can help you wipe it out for good. Check out these tips for using the best cleaners to solve your fungus problem.

How to Freeze Spinach

Freeze fresh spinach leaves—homegrown or store-bought—to create your own dark leafy green to flavor hot dishes and smoothies.

How to Care for Poinsettias

Poinsettias bring a splash of festive red and green to a table or windowsill at the holidays. With proper care, you can enjoy these beautiful plants for weeks.

1,000+ Photos

Browse beautiful photos of our favorite outdoor spaces: decks, patios, porches and more.

Follow Us Everywhere

Join the party! Don't miss HGTV in your favorite social media feeds.