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How to get rid of grubs in the lawn?

By Fafard

Did you know that white grubs are actually larvae of beetles including the common chafer, European chafer or Japanese beetle? In fact, these small worms, about 1.25 cm (0.5 in.) long, have a soft, white, C-shaped body with small legs near the head. They live in the soil and feed on the roots of the lawn, causing your lawn to die.

Signs to watch out for

Your lawn may be infested with grubs if you notice irregularly shaped brown spots, patches of dead grass that lift up easily and/or holes dug by animals that come to feed, such as skunks and raccoons. In all cases, simply lift a few damaged patches of your lawn to confirm the presence of larvae in the soil. If you count more than 5 grubs per square foot, you must take action!

An effective and proven solution to the #1 lawn care problem

With the update of the Quebec pesticide management code in 2019, solutions to control grubs are reduced. Products containing imidacloprid are now banned in Quebec. Fortunately, there is now the Scotts® Grub B Gon MAX® Grub Killer. It's active ingredient (Bacillus thuringiensis subsp.galleriae) is a live organism that is effective against a variety of beetle grubs, including June beetles and Chafers.

Here are the main benefits:

  • Effectively Kills Grubs!*
  • Shelf stable, no refrigeration required**
  • Easy, familiar application method - can be applied with a Scotts® spreader

* Effective against the following larvae: Asiatic garden beetle, Black turfgrass ataenius, European chafer, reen June beetle, Japanese beetle, May or June beetles, Northern masked chafer, Oriental beetle, Southern masked chafer, and Annual bluegrass weevil larvae when applied at label rates. Refer to the product label for details.

**Store at temperatures between 4-25ºC. Used within 17 months from the date of manufacture.

When and how to treat a grub infestation?

Unlike some insect pests, lawn larvae have an annual life cycle. Therefore, several applications of the Scotts® Grub B Gon MAX® Grub Killer can be made during the season.

April - May

The larvae that overwinter in your lawn migrate to the surface to feed on the roots of your lawn. This is the ideal time to eliminate them by applying the product as soon as the soil thaws.

Meanwhile, skunks, raccoons and birds take advantage of this time to plow your lawn to find this food. Take this opportunity to put damaged lawn patches back in place by applying good pressure so that the roots are in contact with the soil. Water deeply to facilitate the recovery of the lawn.

Late May

The grubs sink into the soil and stop eating the roots of the grass. There is no need to apply a treatment. However, this is the ideal time to repair damaged areas. To learn more about this subject, click here. Unfortunately, it may even be necessary to redo the lawn depending on the extent of the damage.

End of June

When the 'Stella de Oro' daylilies and hybrid tea roses are in flower, the larvae hatch and the adult beetles surface. You will then notice Japanese beetles feeding on the leaves and flowers of your plants. This is the period of nuptial flight. Beetles do not lay their eggs in long grass. It is therefore important to maintain your mowing height at least 8 -10 cm to prevent grub infestation.


It is in the evening, around 8:30 pm, that the adults are busy laying eggs. This period generally extends throughout the month of July. Two or three weeks after laying, the eggs hatch and the larvae begin to feed on the roots of the lawn. An application at the end of July will remove the freshly hatched larvae.

During prolonged periods of heat, a lawn may wilt, turn brown and go into dormancy. This is normal, it protects itself. This period of drought will naturally limit the development of eggs and larvae that prefer humid environments. If you still want to water, water thoroughly, but not too often. Finally, don't forget to turn off outdoor lights to avoid attracting adult beetles.

August - September

The larvae continue their development by feeding on the grass roots. They will burrow deep into the soil around the beginning of October to overwinter. An application at the beginning of September is therefore appropriate to minimize the impact of the larvae the following spring.

The key to a green and healthy lawn is prevention. The healthier your lawn is, the less vulnerable it will be to a grub infestation.