How to Get Rid of Grubs
The Wonder Down Under Your Lawn!
Grubs! Lawn-loving larvae of various beetles, these tiny trespassers lurk beneath the surface of your grass. They feast on its roots, causing unsightly brown patches. So how to get rid of grubs and keep your lawn green? There are different ways, both natural and chemical, to rid your yard of greedy grubs.
A Common Lawn Invader
Nearly all lawns have a few grubs, but they rarely cause trouble unless their population soars. Essentially, there is a “critical mass” where the scales tip from harmless to problematic.
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.
Again- if a square foot of sod that’s 3 inches deep has 5 or more grubs, it’s time to take action.
Battling the Bugs with Bacteria
There are a couple of different micro-organisms that, while harmless to your lawn, are very bad news for grub worms.
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. They release bacteria that multiply, ultimately killing the host grub.
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.
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 Conditions Deter Egg Growth
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. Adult beetles lay their eggs in the summer. If you experience a summer drought, 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.
Chemical Treatment Options
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.
Curative treatments are designed to kill immature larvae. Thus, they 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.
Your other option is preventive products, which stop the next generation of grubs from developing. However, they have little effect on young grubs that are currently chomping away in your grass.
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 own lawn becoming infested. 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 personal buffet.
- Grub worms become a damaging pest when you’ve to 5 or more per square foot in your lawn turf. They eat away at the roots, causing unsightly brown patches.
- Beneficial nematodes are a great way to address grub worms naturally. These microscopic roundworms release a bacteria that invades and kills the grub larvae.
- Beneficial spores, like nematodes, do no damage to your lawn. But they create a condition called milky disease that’s very detrimental to grub worms.
- Dry conditions- especially a hot summer drought- can also assist in purging this subterranean pestilence. Simply let your lawn dry out for a few weeks to kill the grubs, and watch it spring back to life once you resume watering.
- Curatives are chemical treatments that effectively kill larvae. However, they are not effective on organisms that have matured into pupae in the developmental process.
- Preventives are chemical treatments that deter grub worms from invading your lawn in the first place. These are a great tool to proactively protect your lawn if you’ve spotted problem areas in your neighbors’ yards.
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Published on March 31st, 2017
Updated on September 11th, 2019
I’ve been researching and sharing lawn care and gardening info since 2010. I’m no expert, but my neighbors think I am