Detect and Control Grubs

Grubs, or grub worms, are squishy-looking white, C-shaped larvae laid by certain species of beetles, such as Japanese or June beetles, that live in the soil and feed on organic matter like grass roots. Typically hatching mid-summer, grubs can cause serious root injury in your lawn, reducing the ability of your lawn’s grass to take up the water and nutrients it needs to survive. This can lead to visible lawn damage especially during the hot, drier months of the summer when your lawn may already be undergoing heat stress. While most lawns can tolerate some grub worm activity, it’s always best to act fast in remedying this and other pest problems (like chinch bugs) - otherwise, you might be faced with an infestation, which will require a whole lot more time and money to remedy.  

SIGNS OF GRUB DAMAGE

Affected areas of your lawn will appear unthrifty. That is, your grass will thin and turn yellow. You may notice dead patches in your hard, increasing in size as the days pass. Your lawn may also feel spongy, like newly laid sod.

Because grubs feed on the roots of your grass, you may find that you can pull up pieces of your lawn as easily as peeling back unlaid carpet. If this is the case, you’ve got grubs.

You may also notice a lot of animal activity in your yard. Skunks, racoons, moles – these critters feed on grubs. So do many bird species. If you find nocturnal predators or birds in your yard digging up the turf, pay attention; it’s a sure sign of grubs.

PRO TIP: If you find more than five grubs per square foot of lawn, you have an infestation problem.

HOW TO KNOW IF YOU HAVE GRUBS

To verify that grub worms are, indeed, the root of the problem, inspect the soil of these damaged areas from the top to at least 2” in depth, looking for the small white larvae. They should be easy to spot, visible to the naked eye.

PRO TIP: Most problematic beetles arrive early to mid summer to lay their eggs in your yard, so keep an eye out for those unwanted visitors. That’s an early indication that you could have an upcoming grub problem.

HOW TO GET RID OF GRUB WORMS

While the best counter-attack is prevention, everyone knows it’s the defense that wins games. So, before you can go on the offensive, you’ll need to deal with the grubs that have turned your lawn into their own personal buffet.

Why? Because otherwise you’ll be facing an infestation. The best way to make your lawn resistant to pests like grub worms is to restore your lawn to its natural resiliency. While that takes time with the right nutrients and lawn care maintenance, you can address the larvae at the same time you face off against any mature female beetles who may be looking to lay their eggs in your yard.

Your options for getting rid of grub worms:

    • Turn to Integrated Pest Management (IPM), a natural solution that relies on beneficial insects feeding on grubs in your yard. This method is effective, environmentally sensitive and is often a favorite of gardeners due to its lower environmental impact.
    • Experiment with biological control agents such as nematodes (tiny, soil-dwelling worms) and the bacteria they release into the soil. Products containing the nematode Heterorhabditis bacteriophora may help target white grubs. Another strain, bacterium Bacillus thuringiensis, is most effective when applied around the time of peak egg hatch in early August.
    • Use milky spore bacterium. It’s a natural predator of the Japanese beetle grubs and comes in white powder form, to be released on the affected areas of the lawn where (and only when) grubs are present. These spores, while effective, take time to work and can survive in the soil for up to 15 years, continuing to fight against future grub takeovers.
    • Try neem oil. A natural derivative from the seeds of a tree found in India, neem oil can be used as a natural pest control solution against lawn grubs.
    • Use an insecticide like Diazinon which has been around for years but may take 3-4 weeks to work. If you choose to go this route, make certain that the areas you treat have grubs present at the time of application, or you’ll be wasting your time and money.

SOMETHING TO NOTE: A healthy turf with a few grubs may not need insecticide. When healthy turf is supported by frequent rain or irrigation, it can withstand a small grub population of about five grubs per square foot without any visible turf damage.

HOW TO PREVENT GRUB WORMS

A healthy, strong lawn is the key to preventing grub worms from taking over. And that starts with the soil. This means making sure the soil in your lawn is getting the water and nutrients it needs to be the grass-growing powerhouse nature intended it to be. Thick, healthy grass blades can help prevent grub worms since the female beetles prefer to lay their eggs in thin, sparse grass.

You’ll also want to mow high and water deep, two critical lawn care steps that promote the growth of deeper and stronger grass roots. Depending on where you live and your lawn’s grass species, you can look to overseed and topdress your lawn, as well as apply moderate levels of nitrogen to build a strong root system, particularly before grass goes dormant in the winter.