AT A GLANCE
Eat grass roots, causing irregular, burned-looking patches
Damage can appear anytime from late spring through early fall
Most obvious during dry spells
They are the larvae of many kinds of beetles
To control, apply beneficial nematodes or (for Japanese beetle grubs) milky spore disease
In the summer, adult beetles lay eggs on grass blades. When the larvae hatch, they tunnel into the ground and start eating the roots, generally staying within 3 inches or so of the surface. As winter approaches, most species head deeper underground to hibernate. Come spring, they wake up and go on a brief eating binge before pupating. The adults emerge in late spring to mate and start the whole process over again.
White grubs also munch on flower and veg etable roots, but they rarely cause serious damage. If a few healthy plants suddenly wilt, poke through the soil nearby. If you find grubs, either drop the culprits in a bucket of soapy water, or just leave them lying on the surface where birds can have them for lunch.
These pests are the larvae of many different beetles, including chafer, Japanese, June (a.k.a. May), and Asiatic garden beetles. It's all but impossible to tell them apart: They all have fat, whitish bodies that tend to curl up into a C shape. They all do the same dirty work, too, eating the roots of your grass, and leaving you with a lawn full of irregular, brown patches that look burned. If you tug on one of the dead clumps, it'll come right up like a piece of loose carpet-often exposing the culprits in action. Grubs start feeding in early spring, and the damage becomes apparent at any time from late spring through early fall, usually during dry spells.
Many things can cause burnedlooking patches in turf grass. You'll know you've got big-time grub trouble if skunks, moles, raccoons, or crows are paying frequent, damaging visits. They all think grubs are the tastiest snack a critter could ever ask for.
A few grubs here and there won't eat you out of lawn and garden. In fact, like all "bad-guy" bugs, they're an important cog in the wheel of life.
The trouble comes when too many grubs start munchin' on the same chunk of turf. Here's a simple way to take a census: Cut both ends off of a soup can, and sink it into your lawn up to its rim. Then fill it close to the top with water. Repeat the process in several parts of your lawn, with the cans spaced about 10 feet apart. Wait 5 or 10 minutes, then count the grubs that have floated to the top of each can. That number will equal the number of grubs per square foot of lawn. If you've got 8 to 10 bodies per can, don't sweat it: Birds can keep that population under control without wrecking your lawn in the process. More than 10 grubs means you've got a major invasion on your hands, and you need to strike back-hard!
If you know the grubs in your lawn are baby Japanese beetles (because the grown-ups are chewin' the daylights out of your shrubs, flowers, and veggies), get some milky spore disease (Bacillus popilliae), available in catalogs and many garden centers. All you do is sprinkle it onto your freshly mowed lawn according to the package directions, and it stays in the soil for years, killing baby grubs as soon as they hatch, but harming nothing else. Unfortunately, milky spore takes a few years to achieve its full effect, but once it gets up to speed, your grub woes will be gone for good.
For fast-acting relief, drench your turf with beneficial nematodes (available in catalogs and garden centers). These almost microscopic worms burrow into white grubs, reproduce, and at the same time, deliver a bacteria that kills the grubs, but no other critters. In order for the nematodes to do their job, you need to apply them in just the right way, so follow the instructions on the label to the letter. There's one down side to this method: The results are temporary, so you may have to repeat the maneuver .
No matter what strategy you use against white grubs, it's important to attack while they're still small and vulnerable. The exact time frame varies, depending on who the grubs' parents are and what part of the country you live in. That may sound confusing, but there's a simple way to schedule
D-Day. Just do what the old timers did: Keep an eagle eye on your back-porch light. When you see a lot of beetles flitting around, makin' whoapie, you know it won't be long before your lawn's full of baby grubs. Wait five to six weeks, then choose your weapons, and charge! (Or, if you'd prefer a more exact approach to timing, call your closest Cooperative Extension Service and ask when the grubby action starts in your town. They should be able to help you.)
This grub-routing routine is the way to go when you're planning a new lawn, revamping an old one, or replacing turf grass with groundcovers, flower beds, or a vegetable garden. It's simple, too: Just cultivate the soil thoroughly, and you'll bring all the grubs to the surface, where birds will polish 'em off pronto. If you do your digging in spring or early fall, 3 to 4 inches is deep enough. Once the weather turns cool, though, the grubs head deeper; then, you'll need to till the soil from 4 to 8 inches deep.
Once you've got the grub population under control, you need to keep it from skyrocketing again. How? Grab the grown-ups before they have a chance to fill up the maternity wards-that's how! Start handpicking adult beetles early in the season, hang out traps, and encourage beetle-eating helpers like birds and toads.
You could go to the local store and buy "BAYER Advanced Lawn treatment and Grub Control" or any other grub treatment with "imidacloprid" (the same stuff that is used in flea and tick powders, but much stronger)
Bacillus thuringiensis (Bt) is actually a naturally occurring bacterium, common in some soils, that causes disease in certain insects, most notably leaf and needle feeding caterpillars . It was first discovered in the early 1900s. The French were the first to advocate using Bt in the garden and by the 1960s, Bacillus thuringiensis products were available on the open market and were readily embraced by the organic gardening community.
Controlling pests with Bacillus thuringiensis is dependent on its active ingredient, a crystal protein, which paralyzes the digestive system of the insect. The infected insect stops feeding and starves to death. While the original strains of Bt pest control were directed at caterpillars such as tomato hornworms , corn borers  or earworms , cabbage loopers  and leaf rollers, new strains have been developed to attack certain flies and mosquitoes . Bacillus thuringiensis products have become an essential weapon in the battle against West Nile Virus. Some field crops, such as corn  and cotton , have been genetically altered to contain the gene for the crystal protein in their plant structure.
All in all, controlling pests with Bacillus thuringiensis has become a marvelous tool for eliminating certain insect species from both the commercial and home garden. Its use helps reduce the amount of chemical insecticides in our environment and is harmless when eaten by beneficial insects and animals. Study after study has shown that using Bt in the garden is perfectly safe in its application and ingestion by humans.
Now that you have the answer to what is Bacillus thuringiensis, it probably sounds like Bt pest control is the only way to go, but there are a few things you should know about Bacillus thuringiensis products before you begin.
First and foremost, read the label. You donít need to use Bt in the garden if you donít have the pests it eliminates. Bacillus thuringiensis products are very specific in the insects they will or wonít kill. As with any pesticide Ė manmade or natural Ė there is always the danger of insects becoming immune and you donít want to add to that problem with overuse.
Secondly, Bt will only affect those insects that actually eat it, so spraying your corn crop after the larvae have made their way inside the ear will be of little use. Timing is crucial, so the observant gardener wonít try to spray the moths or eggs, only the leaves the larvae will eat.
For those specified insects that do ingest the Bt product, be aware that starvation can take days. Many gardeners who have previously applied only chemical pesticides are used to the immediate effects on insectís nervous systems and, therefore, think Bt pest control doesnít work when they see the insects still moving.
Bacillus thuringiensis products are highly susceptible to degradation by sunlight, so the best time to spray your garden is early morning or evening. Most of these products adhere to the foliage for less than a week following application and the period shortens with rain or overhead watering.
Bt pest control products have a shorter shelf life than most chemical insecticides and should be stored in a cool, dark place. Itís best to buy no more than can be used in a single season, although manufacturers generally claim a reduction in effectiveness after two to three years. The timeline for liquid applications is even shorter.
If your garden is bothered by any of the susceptible insects, Bt pest control might be something to consider. Controlling pests with Bacillus thuringiensis can be an effective and environmentally friendly way to treat your garden. Knowing about what Bacillus thuringiensis is and how and when it should be used is the key to its success.