No, those aren’t fried cheese curds on your Wisconsin lawn — they’re grubs! To get rid of them, apply grub control between May and July and from August to October, with a few exceptions depending on the type of grub.
The best approach is a combination of preventive and curative treatments, but don’t worry, we’ve got you covered. This article will tell you everything you need to know so you can time your treatments perfectly and get rid of these insects as soon as possible.
Chemical grub control schedule
There are two main approaches for chemical grub control: preventative treatments and curative treatments:
- Preventative treatments are insecticides designed to target small grubs before they lay their eggs, making early application crucial for effectiveness.
- Curative treatments are insecticides meant to deal with an existing grub infestation that needs immediate attention.
Timing is key for both approaches — applying products at the wrong time can waste your efforts and the product itself. You can also learn how to do it in our guide: “How to Get Rid of Grubs in Your Lawn.”
So, let’s take a look at the timing for each approach:
When to apply preventative treatment
The timing for applying preventative grub control depends on the type of grub in your Wisconsin lawn, but it generally falls between late spring and summer. Here is the specific timing by type of grub:
- Japanese beetle: June to July
- May/June beetle: May to early June
- European chafer: May to late July
- Northern masked chafer: May to late July
To ensure the most effective results, it’s best to apply the treatment early in these windows. By doing so, you can have the treatment in place before grubs lay their eggs.
Preventative insecticides include products containing chlorantraniliprole, cyantraniliprole, dinotefuran, imidacloprid, and others.
Pro Tip: Did you know there is also an ideal time window to apply crabgrass preventative treatments? Check out our article — “When to Apply Crabgrass Preventer in Wisconsin” — for more information.
When to apply curative treatment
Curative treatments can tackle grub infestations when they’re already damaging your lawn. The timing of these applications also varies depending on the type of grub, but it’s typically from late summer to fall, which is when the grubs are larger and more active.
Here are the time windows by grub species:
- Japanese beetle: August to October
- May/June beetle: July to September
- European chafer: August to October
- Northern masked chafer: August to October
Curative insecticides include products containing carbaryl, trichlorfon, and others.
Pro Tip: This timing is also the best time to plant grass seed in Wisconsin, so you might want to overseed your damaged lawn after the grubs are gone.
Biological grub control schedule
For a more natural approach to grub control, you can use beneficial nematodes (Heterorhabditis bacteriophora) or a special strain of Bt (Bacillus thuringiensis galleriae) to keep grubs in check. Nematodes are microscopic organisms that parasitize and kill grubs, while Bt is a bacteria that reduces insect feeding.
These biological controls should be applied during the same window as preventive treatments, from late spring to summer, as they are more effective against early instar grubs.
Non-chemical grub control schedule
The best way to prevent grub damage and keep your lawn healthy without using insecticides is by sticking to a month-to-month Wisconsin lawn care calendar. A well-maintained lawn is more resilient and better able to withstand grub feeding. Here’s what that schedule should include:
- Watering: Make sure your lawn gets the right amount of water, but not too much, as female beetles look for moisture when laying their eggs. Ideally, you should stop watering during summer so the eggs dry out and die.
- Mowing at the correct height: Keep your grass mowed at the appropriate height for its type to encourage deeper roots and stronger growth. If you don’t know which grass you have, you might want to check out our guide: “The Best Grass Seed for Wisconsin Lawns.”
- Fertilizing: Regular fertilization strengthens your turf, making it more resistant to grub damage. For information on timing, check out our article: “When to Apply Weed and Feed in Wisconsin.”
- Dethatching: Keep the thatch layer to a minimum, as grubs can feed on it. Read more on: “The Best Time to Dethatch Your Lawn in Wisconsin.”
- Aerating: Aerate your lawn to encourage deeper root growth and discourage beetles from laying their eggs in compacted soil. Learn when to do it in our guide, “The Best Time to Aerate Your Lawn in Wisconsin.”
How to identify Wisconsin grubs
Douglas S. Richmond | Purdue University
We know what you’re thinking — how am I supposed to know what the different types of grubs look like? Don’t worry; we’ve got you covered. Here are some key characteristics to help you identify their larvae so you can apply grub control at the right time:
- Japanese beetle: Look for spines on the underside of the tip of their abdomen in a V shape. They grow from 1/8 inch up to about 1 inch long. The damage they cause resembles drought stress.
- May/June beetle: These grubs have two parallel rows of short spines that look like a zipper and grow up to 1 1/2 inches long. They have a reddish-brown head.
- European chafer: About 1 inch long, with two nearly parallel rows of dark hair at the tip of the abdomen, like a slightly open zipper.
- Northern masked chafer: Around ¼ inch long, they are translucent and turn grayish after feeding. The tip of their abdomen features evenly spaced, non-uniform hairs.
Still stumped? Contact your County Extension service for a proper ID on the type of grub eating your lawn.
More lawn care resources for Wisconsin
Caring for your lawn in the Badger State doesn’t stop with grub control. To help you tackle all aspects of lawn care and landscaping, we’ve gathered a few helpful guides:
- When Does Grass Stop Growing in Wisconsin?
- The Best Weed and Feed for Wisconsin Lawns
- Should You Plant a Clover Lawn in Wisconsin?
- When to Plant Clover in Wisconsin
- The Most Common Weeds in Wisconsin
- The Best Ornamental Grasses for Wisconsin
- The Best Ground Cover Plants for Wisconsin
When to call a professional
Although knowing when to apply grub control in your Wisconsin lawn is a great step towards reclaiming it from those pesky pests, that doesn’t mean you have to do it yourself.
Consider giving a local lawn care service a call. They have the expertise to handle all of your lawn problems while you just relax and enjoy what the state has to offer.
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Main Image Credit: Jason A. Bleecher | Adobe Stock Free | License
