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Spring Grub Questions

April 15, 2014

Lots of grub questions this spring!

When is the best time to put down GrubEx?

The number 1 question I get in spring is when is the best time to apply GrubEx since the package says to apply spring to late summer? You will also note a direction on the package to not apply to waterlogged soils and to water after application. Since the soils tend to be very wet this time of year and since the grubs will not be laying their eggs until summer, I asked our researchers when they apply GrubEx to their lawns. Their answer: Early May. (If you are reading this and May is in your rearview mirror and you have not put your GrubEx down yet this year, apply as soon as you can up until late summer.) A single application of GrubEx will then prevent the next generation of grubs, that will hatch this summer, from attacking your lawn.  (Click here to learn more about GrubEx.)

When do grubs do the most lawn damage?

Most grub damage is done in fall, however some folks do not notice they have a problem until sections of their lawn look dead in spring because the roots are gone. Sometimes the lawn can be peeled back like a carpet. In extreme cases you may see raccoons or crows tear up the lawn looking for grubs to eat.

Grubs eat grass roots resulting in brown, dead lawn patches in fall and early spring

Grubs eat grass roots resulting in brown, dead lawn patches in fall and early spring

Here is the grub life cycle:

In early spring mature grubs awaken from hibernation and begin to work their way up from deep in the soil to just below the grass surface. In late spring, these grubs change into a pupae stage before turning into beetles that later feed on roses and other shrubs and trees in your landscape.

In summer, beetles burrow into the lawn and lay eggs that will hatch into grubs.

In late summer and early fall, newly hatched grubs feed heavily on your grass roots before hibernating for winter. It is during this time that young grubs do the most lawn damage as they gorge themselves prior to hibernation.

(Click image to enlarge)

(Click image to enlarge)


I treated for grubs, why do I still have moles?

GrubEx doesn’t harm earthworms, which are so beneficial to your soil. Even though you rid your lawn of grubs, you may still get the occasional mole in your lawn feasting on your earthworms.

Click here to get info covering how to rid your lawn of moles.

Should spring grubs be treated?

If you find grubs when digging in your soil during spring the first thought is to rush to get a treatment on your lawn. There are two reasons that you may not need to worry about spring grubs. First, they do not feed in late spring when they are making the shift from the grub stage to the pupae stage prior to becoming beetles. And second, if your lawn looks healthy in spring it can tolerate a few grubs without sustaining damage, especially if there are less than five grubs present per square foot.

For lawn questions, click here to see how to contact the Scotts Help Center.

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  1. larry devito permalink

    you recommend applying grubex prior to a soaking rain, but also recommend a light watering after application. isn’t that contradictory? or did i read the answers incorrectly?

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