They don’t care who you are or where you live. You won’t see them coming, and by the time they make their presence known, you could have a full-blown infestation on your hands. Grubs! Lawn-loving larvae of various beetles, these tiny trespassers lurk beneath the surface of your grass, feasting on the roots and causing unsightly brown patches. We’ve put together the best ways, both natural and chemical, to rid your yard of greedy grubs.
MATERIALS AND TOOLS
- Hb nematodes
- Milky spore
- Curative grub control with trichlorfon
- Preventative grub control with imidacloprid or halofenozide
INVASION OF THE LAWN SNATCHERS
Nearly all lawns have a few grubs, but they rarely cause trouble unless their population soars. The best way to determine if you have a grub problem is to remove a square foot of sod, about 3 inches deep, from the center of a brown patch. Sift through it and look for milky white C-shaped larvae. The buggers can vary in length, from ½ inch to 1 inch, depending on the species of beetle they will eventually become. If you find five or more grubs in the sod you removed, it’s time to formulate a treatment plan. While some products work best on larvae of particular beetles—whether June bugs, Japanese beetles, or other beetles—the treatment options are broadly the same.
THE BATTLE OF THE BUGS
If you’re looking for a natural way to rid your lawn of grubs, consider treating it with beneficial nematodes. Nematodes (typically of the Heterorhabditis bacteriophora, or Hb, variety) are microscopic parasites that invade the grubs’ bodies, releasing bacteria that multiply and ultimately kill the host grub. In the meantime, the nematodes mature and propagate, and a new generation of nematodes emerges from the dead grub. It can take up to three years for nematodes to establish a colony large enough to eradicate a large population of grubs, but going this route means you won’t have to treat your lawn with chemicals. Be sure to order from a reputable nursery; nematodes are living organisms that must be transported with care (usually refrigerated) and applied soon after they arrive.
SPREAD SOME SPORES
Available in a powder from your local garden or home center, the Bacillus popilliae spore, sometimes called milky spore, creates a bacterial environment in the soil known as milky disease. It won’t harm your lawn but it’s deadly to grubs, specifically to the larvae of the Japanese beetle. Like nematodes, milky spore isn’t a quick fix. It takes a few years to develop enough of the beneficial spores to rid the yard of grubs, but once established, the “disease” will continue to ward off grubs.
DRY THE CRITTERS OUT
Beetle eggs need moisture to survive, so if you have a grub problem, you can try making your lawn as inhospitable to grubs as possible. If you experience drought conditions during the summer months, when adult beetles lay their eggs, take advantage of the dry conditions by making a conscious decision not to water your lawn for three or four weeks to further dry out the soil. The eggs will eventually die, which will reduce next year’s crop of larvae. Your lawn will dry out, too, but as long as your grass is in good condition, it should spring back to health when you resume watering.
ENGAGE IN CHEMICAL WARFARE
Chemical-based grub-control can be very effective, but keep in mind that it’s toxic and can kill beneficial insects at the same time it kills grubs. Such treatments fall into two categories: curatives and preventives. Curatives, which are designed to kill immature larvae, should be applied in late summer or early fall when young grubs are actively feeding on grass roots. Look for a product that contains trichlorfon (Dylox is a popular brand name), which is the best option if you’re in a hurry to get rid of the little munchers. It will not, however, affect grubs that have developed into pupae, which, depending on the species, could survive another year or two before developing into beetles.
If you’ve had a grub problem in the past, or if you’ve spotted telltale brown patches in your neighbor’s yard, applying a preventive grub-control product will reduce the risk of your lawn becoming infested. Preventive products stop the next generation of grubs, but they have little effect on any young grubs that are currently chomping away in your grass. Look for preventive products that contain either imidacloprid, such as the insecticide Merit, or halofenozide, such as Mach 2, to keep grubs from turning your lawn into their private dining spot.