As summer begins to evolve into fall, it leaves behind a voracious creature with an insatiable appetite for grass roots. I’m referring to lawn grubs.
Grubs are the larvae of Japanese beetles and European chafer beetles. Many of you have already been introduced to the parents of the grubs that will be feasting on your lawn this fall. They’re last year’s grubs in their adult stage – the big brown beetles that have been flying around. They make a nuisance of themselves by flying into the glass of your windows. Because they started this aggravating ritual a couple months ago, both species of beetles are commonly called June bugs.
Aside from their unpredictable flight patterns, June bugs are harmless to humans. Their navigation instinct may have been short circuited by their mating instinct. Once successful, the females lay their eggs in turf. When the eggs hatch, the small grubs burrow down into the sod and begin feasting on the grass roots.
As the weather gets colder, the well-fed grubs burrow further down in the ground where they overwinter. When the ground warms up in the spring, they’ll come back up and continue feasting until it’s time to pupate and morph into adult June bugs.
Don’t be lulled into complacency because you didn’t experience June bugs smacking into your windows. They aren’t restricted to laying eggs in any one spot. You may still have their progeny in your lawn. There’s an easy DIY check to see if you have grubs. Cut a one foot by one foot square of sod from several areas of your lawn. Fold back the sod. Look for any white, crescent-shaped creatures like in the photo. Check both the bottom of the section of sod and the hole from which you took it. If there are six or fewer grubs per test area, treatment is optional. There are too few to do any damage. Seven or more call for control measures.
Grubs have been destroying area lawns for decades so there are several effective grub control products available at garden and home centers, including one that’s manufactured locally. The products are granular and spread with the same spreader that you use for fertilizer.
The product label may say that it can be applied in spring or fall but a fall application is more effective. The grubs will have just hatched so they’ll be small and weak. By next spring, they’ll be well fed, strong and several times bigger than they are now. As a result, you may have to make more than one application in spring but only one in fall.
Another reason for a fall application is that the fully grown grubs will damage your lawn. You’ll see brown spots where they’ve eaten the roots. In the fall, the young grubs are eating less, causing less surface damage.
Lawns on our lawn care program receive grub control in the fall if they need it. We can also apply grub control for those not on our program if you don’t want to bother checking for grubs and applying control yourselves.
Their damage is generally minimal in our lawns. However, skunks cause more damage when they dig them up.