Grubs, whatever the species, are plump, fleshy, white to bluish white to gray in color, C-shaped, ¾ of an inch to 2 inches in length, have six legs, and a brownish head.
Japanese Beetle Grub
The three most common species of white grubs in North America are Japanese beetle grubs, June beetle grubs, and European chafer beetle grubs. White grub damage is generally characterized by patches of dead or dying grass in the lawn. Affected grass is brown and wilted, looks burned, and rolls easily away from the soil. Grub worm damage is usually worst in April and May when grubs move up to the soil's surface, and then again in September and October before they head back down. Perhaps the worst thing about lawn damage from grubs is that the grass rarely recovers. People just have to live with patchy grass for the season while they get grass grubs under control.
Figure out if grub treatment is necessary. To do this, grab a shovel, pick a spot in your yard where brown grass meets green, and cut three sides of a 1 sq ft chunk of sod. Half of the square should be in the green, half in the brown, and you should cut down about 4 inches. Cut one line in the brown, the two side lines, and leave the line in the green attached. Once the three parts of your square are cut, try to peel the sod back. If the brown grass rolls back easily, the roots have been eaten and you have lawn grub worms. If you see 6 or more grubs per square foot, you have a problem.
Kill grubs with Milky Spore. This is probably the number one most recommended product for white grub control. Milky Spore is the commercial name for the bacteria Bacillus popillae. This bacteria, once spread on your lawn, enters grubs and only grubs, and sets about killing them. Beneficial critters are safe. In climates where the soil is moist and at least 70°F, Milky Spore Grub Control can work its magic in as little as two weeks. If you don't have those soil parameters, it will still work for you, but may take a little longer. Once Milky Spore is established in your soil, it can provide you with season-long grub control for 15 years or longer.
Control grubs with beneficial nematodes. If you want to get rid of grub worms, the efficacy of beneficial nematodes is right up there with Milky Spore. They're perfectly safe for you, your pets, earthworms, and most beneficial insects. These little guys are nothing more than microscopic worms that get sprayed onto your lawn. Once there, they find their way into white grubs. Once inside, they emit a bacteria that more or less liquifies the grubs' innards so that the nematodes can devour them more easily.
Kill grubs with grub insecticides. There are numerous commercial grub pesticides available that rely on various chemicals for killing grubs. Merit 75 uses imidacloprid, Dylox uses trichlorfon, Sevin uses carbaryl, Mach 2 uses halofenozide, and Scott's GrubEx uses chlorantraniliprole. While there are many other products that will control white grub pests, the ones I just listed are well known and highly effective. Most of them can be applied as powders, dusts, granules, and/or liquids. Be certain to read the directions for whatever grub control product you decide on. Keep in mind that every grub pesticide has the potential to be harmful.
Keeping grass long, thick, and dry is good for grub worm control. The beetles that lay the eggs that hatch into grubs prefer laying those eggs in areas with short, sparse grass. Keep grass at least two inches long. Also, grub worm eggs need plenty of moisture in order to hatch. If your lawn can handle it, don't water at all. Otherwise, start doing a few deep waterings instead of lots of light waterings. Not only will this cause eggs to be exposed to water less frequently, it also forces grass to grow longer roots which will enable it to withstand more grub damage before dying.
No adults = no babies. One of the best things you can do to control grubs is to control the adults. In general, this means controlling Japanese beetles. Since there is far more to that little task than I have room for in this paragraph, I will direct you to the article on Japanese Beetle Control.
Overseed your lawn every spring and fall. The thicker the grass is, the less likely it is that lawn grub eggs will be lain in it.
Pick up dead plant material from gardens. Very young grubs eat decaying plant material.
Fall plowing works quite well for killing garden grubs. Plowing should be done before the grubworms burrow too deep underground because of frost.
Encourage robins to kill grubs for you. Place a couple bird baths and nesting platforms around your yard to entice robins to stick around.
Hand picking is another effective means of controlling garden grubs. As you till or weed your garden, carry along a bucket of soapy water to collect grubs.
Neem oil kills grubs. Neem oil is a derivative of the neem tree. It works as an insecticidal soap, an IGR, and as an antifeedant to kill grubs.
Control white grub worms with pyrethrins. Pyrethrins are another natural grub killer, are derived from the chrysanthemum flower, and work well for killing grubs when used as a soil drench.
Use beer as a grub killer. Make a homemade grub trap by digging a hole in the garden, placing an old Cool Whip container in that hole so that the top of it is flush with the ground, and pouring a couple inches of (cheap) beer in it.
Kill lawn grubs with aerator sandals. Aerator sandals strap onto your boots or shoes and have little spikes that penetrate into the soil. Not only do they aerate your lawn, they also kill grub worms. Studies have shown that wearing them can reduce lawn grubs by as much as 56 percent. Sure, you'll look like an idiot river dancing across your grass, but you will have the satisfaction of knowing that you are a lean, mean, grub-killing machine.