The first step to ridding your lawn and garden of any pest is positive identification. Before we discuss getting rid of lawn grubs, let’s first establish exactly what lawn grubs are.
What Are Lawn Grubs?
Lawn grubs are the larvae of June bugs, Japanese beetles and other scarab beetles. These adult beetles lay eggs during the summer and autumn, and the larvae hatch out of the eggs late in the summertime and throughout the fall.
Once hatched, the grubs burrow down into the soil and consume plant roots and other organic matter during the cold winter months. During this time, they are fat, white, C-shaped critters that go by a number of common names, including:
- White Grubs
- Grub Worms
- Lawn Grubs
In the springtime, the larvae transition into pupae and then mature into beetles. The beetles dig their way out of the soil in early summer, munch on plant leaves, breed and lay more eggs.
What Damage Do Lawn Grubs Cause?
In small numbers, lawn grubs don‘t cause a great deal of damage. A healthy lawn can support a small population (e.g. 5 per square feet) without much damage. Problems arise when their numbers exceed 10 per square feet.
Large numbers of Japanese beetle grubs will eat lots of grass roots and other valuable organic matter underground. When they eat grass roots, they destroy the root system.
This deprives your grass of water and nutrients, so the grass naturally turns brown and dies.
Lots of grubs in the soil will attract natural predators to your yard. Visiting raccoons, moles, armadillos and the like will come in search of these tasty morsels and will leave your lawn full of holes.
How Can You Tell You Have Lawn Grubs?
You may notice brown patches in your yard, and you may notice that lots of wildlife is visiting your yard. If you are lucky, though, you’ll discover the grubs before these signs and symptoms occur.
In the springtime, when you are cleaning up your yard before summer, you may find lawn grubs hiding under brush piles and rocks.
When you till your garden, you may turn up a few lawn grubs.
Throughout the summer, be on the lookout for spongy-feeling areas in your lawn. This is an early warning of grub worm infestation that occurs before grass begins to turn brown.
In the late summer and into the early fall, you may begin to notice oddly shaped brown patches in your lawn. This is an indication that you have beetle grub actively feeding in preparation for the long winter months.
When this occurs, you may be able to locate the grubs by pulling back sod in the affected areas. If it peels back easily, you probably have lawn grubs. You may see the grubs just below the turf, eating away at your grass roots.
If you don’t find grubs in the browned areas of your lawn, consider some other causes of grass browning. Shady areas of your lawn may turn brown for lack of sun. Grass may die for lack of water (or too much water).
What Can You Do When You Find Lawn Grubs?
If just a small area is affected, remove the grass and dig down to see if you can locate and remove the grubs. Dig about a foot deep and remove the soil and the turf in that area. Remove the grubs and replace the soil and turf.
Count the grubs you have removed. If you have a total of less than 5 per square foot, focus your efforts on keeping your lawn healthy. If you have more than 5 per square foot, you’ll need to consider some treatment options.
All-in-all, natural, organic lawn treatments are preferable to harsh and potentially dangerous chemicals.
How To Control Grubs Organically
When you control pests in your yard and garden organically, it’s best to devise a comprehensive Integrated Pest Management (IPM) system. With this concept, you draw on a wide variety of natural substances and beneficial insects to help you keep grub worms away.
Here are 12 of the Best Options:
Use Beneficial Nematodes
Beneficial Nematodes are very tiny, unsegmented worms that dwell in good garden soil. The species called Heterorhabditis bacteriophora (Hb nematodes) are especially suited to help with the control of white grub worms.
They provide grub control by hunting down the grubs, entering the creatures’ bodies and releasing bacteria that is deadly to grubs.
You can buy Hb beneficial nematodes through gardening catalogs and online. When you receive your tiny garden grub control helpers, wait until the end of the day to release them onto your lawn. Exposure to sunlight will cause them to become sterile.
Be sure to water well before and after setting them loose. To introduce them to your lawn, follow packaging instructions. Typically, you would mix them with water and then distribute them with a specialized hose-end sprayer or a watering can.
Make Your Yard Bird-Friendly
Grubs are a favorite meal for birds, and of all the critters attracted by grubs, birds will do the least damage.
Add some bird feeders, houses, and a bird bath to your yard and you’ll soon have a host of attractive, cheerful garden helpers standing at the ready to help with your grub control, as well as other pest insect problems.
Keep Chickens, Guineas, Geese or Ducks
All manner of fowl love grub worms. You can turn your barnyard flock loose on your lawn at intervals to seek out grubs and their beetle parents. A flock of ducks, geese, chickens and/or guineas can also help you get your garden plot ready early in the spring. Allow them to stay in the area for a day or two to naturally turn the soil and seek out any pests that may be lurking.
Follow a Wise Watering Schedule
Very wet soil is quite welcoming to grub worms. Instead of watering a little bit, often, water deeply once a week. This is better for your grass root system, anyway.
If you are experiencing a water shortage, allow your grass to go dry and dormant in the summer. This dry spell will kill grubs off that may be lurking in your soil. Your grass will return when cooler temperatures and rain return.
Use Grubs for Fishing Bait or Feed Your Exotic Pet
Till up areas where grub infestation is suspected and collect the little devils. They make great fishing bait. Alternately, if you don’t use any chemicals on your lawn and you happen to have a pet parrot, lizard, turtle or big fish, they make good exotic pet food!
Use Neem Oil
Discourage The Beetles
In addition to Neem oil, there are a number of natural repellents that will prevent beetles from hanging around your yard. Natural ingredients such as lemon juice, garlic, chili peppers and organic soap in the right combinations work well to repel beetles and other insect pests.
For recipes, see our article of Organic bug killer recipes.
Kill Grubs With A Borax Solution
You have to be a bit careful with this idea because too much borax will kill your grass, but if you have a heavy infestation, it may be worthwhile to start out with a targeted application of borax-water.
To do this, mix a tablespoonful of borax into a quart of warm water and spray liberally in areas where you know you have a heavy grub infestation. You may need to repeat this targeted application several times to kill all the grubs in the area.
If You Have Japanese Beetles, Use Milky Spore
Milky spore is an ecologically friendly, non-toxic bacteria that targets Japanese beetle larvae. You can safely use it in conjunction with all of the organic grub solutions listed above. Begin by applying it to your lawn a couple of times a year for the first three years. After that, it will remain active for a decade or more.
Clear Lawn Thatch
Sometimes it’s a good idea to have some thatch in your lawn, but if you are dealing with grubs, you need to get the thatch out of the way before applying treatments.
Beetles like to lay eggs in thatch, and grubs like to hide under it. Furthermore, it can interfere with treatments such as nematodes and milky spore by keeping them from soaking deeply into the soil.
Keep Your Lawn Well-Aerated
Throughout much of their life cycle, lawn grubs live in the top couple of inches of the soil. Aerating your lawn makes this area less hospitable to them, and the act of aerating may very well kill them directly.
Be Consistent In Treatment
Beetles tend to come back to the same areas, year-after-year to lay eggs. If you are dealing with lots of beetles and grubs this year, you can expect some to resurface next year, no matter how diligently you combat them.
Use all the organic tools at your disposal in a consistent and ongoing manner. It may take two or three years to see a real reduction in beetle and grub numbers.
Is Organic Grub Treatment Really Best?
As with many pest insects, if you keep a healthy yard and garden, you are unlikely to be overrun by lawn grubs.
For this reason, it is always better to put your focus on keeping your plants and your grasses strong and healthy than on killing off pests.
Use of pesticides is harmful to beneficial insects, birds, reptiles and other wildlife. Additionally, pesticide runoff pollutes waterways, and excessive chemical pesticides seep into the water table.
Controlling grubs by implementing an organic IPM system does take some time and patience, but the results are long lasting and benefit you, your neighbors, local wildlife and the environment at large.