When To Apply Grub Control

How To Control and Kill Grubs with Scotts and Bayer

The key to controlling grubs is to kill them before they hatch. Apply grub control in spring or early summer.  By applying in spring or early summer, you will be using a preventative grub control product.

Looking for grub control? The top selling products are Scotts Grubex and Bayer Grub Control. Learn when to apply grub control and how to apply. Effective grub control with chemicals begins with a proven product like GrubEx from Scotts or Season Long Grub Control by Bayer Advanced.

Both products are in Lowes and Home Depot stores and both are effective insecticides that control grubs in lawns. For non toxic organic grub control, see my article on Milky Spore. If you have ever had grub problems in your lawn you don’t want them again.

So When Is The Best Time To Kill Grubs?

This time of year we always  get the question:  “When is the best time to spread grub control on my lawn?” The answer? The best time to apply grub control is after you see Japanese Beetles in your yard which is usually between late May and late July.

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That’s right.  After you see Japanese Beetles and here’s why

You want to apply your lawn treatment when grubs are newly hatched or just before.  Because GrubEx and Bayer target the larval stage of many insects, the best time to apply it is when the beetles burrow into lawns to lay their eggs — in late spring to early summer. When the eggs hatch, the emerging larvae are killed so they cannot develop into mature insects

Grubs are the larvae of Japanese Beetles. When they hatch, they begin eating the roots of your lawn. If left untreated, they can chew through huge sections of grass  sometimes ruining an entire lawn in one season.  They will continue to infest your lawn and return the following year to do even more damage.

Lawn damage you see in spring actually occurred the previous fall. You can tell if you have grubs if you see brown patchy spots on your lawn. Those are sometimes mistaken for dry areas or pet damage. To tell the difference just pull the sod up. If the sod remains attached to the soil, it’s probably not grubs.

However, if the sod comes up relatively easily, then you have grubs. When you pull up the sod, you’ll see them curled up on the dirt in a white half-moon shape. These C–shaped creatures feast on the roots of your grass.  Since it takes a while for sod to turn brown, even green grass can have a grub infestation.

When is the best time to put down Grub Control?

Since there is such a wide time frame listed on the packages, when is the best time to apply grub control?  Whether it’s a Japanese Beetle, European Chafer Beetle or June Bugs, grubs  are simply not feeding in the spring time so they can not ingest any insecticide like Grubex or Bayer that has been applied.

As temperatures continue to warm up, the grub will become a beetle.  Early to mid summer is the time of year when beetles do damage to plant material and your lawn. This is the time of year when the life cycle of a grub truly begins.

Beetles will mate in the summer and lay their eggs in the lawn and begin the whole thing over again. Grubs typically hatch towards the middle of the summer and begin to feed heavily on the roots of the turf into early fall.

It is during this feeding period when grubs will ingest the chemicals designed to kill them such as a pesticide.  If they go untreated they will burrow down in the soil to escape cold temperatures and then surface in the spring of the following year to start the process over again.

Update 2018: Michigan State University has an excellent article on grub control. You should be able to find most products at your local Lowes, Home Depot and Menards stores.

MSU: How to choose and when to apply grub control products for your lawn

Michigan State University listed the following preventive products in their research.  They are now recommending a slightly earlier application time than previously.  Best results for Grub Control application by July 15.

Preventive Products For Grub Control

Preventive products are the most effective. Products containing imidacloprid, thiamethoxam, clothianidin or chlorantraniloprole will not control grubs in the spring. They are preventive products that work very well on newly hatched grubs present in July, but do not work well for large grubs found from September to May.

Scotts Grub-Ex – Granular
chlorantraniliprole 0.08%
Apply between April 1 and May 30 (no later than July 15) for best results.

 Bayer Advanced Season-Long Grub Control and Turf Revitalizer – Granular
imidacloprid 0.25% and a low fertilizer rate (6-0-1)
Apply between June 1 and July 15 for best results.

 Local Distributors: Premium Grub Control (Do not confuse with “Premium Insect Control”)
imidacloprid 0.2% – Granular
Apply between June 1 and July 15 for best results.

Bayer Advanced Complete Insect Killer Liquid attach-to-hose-bottle
cyfluthrin 0.36% and imidacloprid 0.72%
Apply between June 1 and July 15 for best results.

Bayer Advanced Complete Insect Killer Granules – Granular
cyfluthrin 0.05% and imidacloprid 0.15%
Apply between June 1 and July 15 for best results.

Curative Products For Grub Control

There are two chemicals, carbaryl and trichlorfon, that are considered curative treatments. They are short-lived compounds that kill all life stages of grubs. These two insecticides are the only options if high numbers of grubs are found in the fall and in spring before early May. MSU research indicates they will kill 20-80 percent of grubs when applied in September or 20-55 percent when applied in late October.

Sevin Lawn Insect Granules – Granular
carbaryl 2.0%
Apply in spring or fall to active grubs.

Bayer Advanced 24 hr Grub Killer Plus – Granular
trichlorfon 9.3%
Apply in spring or fall to active grubs.

Products that will NOT kill grubs

This product will not kill grubs at any rate. This product was tested by MSU for grub control in 2006 and gave identical results as the untreated plots.

Spectracide Triazicide Insect Killer for Lawns – Granular
gamma-cyhalothrin 0.05%

This above information was published by Michigan State University Extension.

Damage from grubs in lawns usually shows up mid July to August. However, my experience has been that grub damage sometimes does not become obvious until September or even into October. Damage may appear as drought stress like brown coloring or wilting.

By September grubs are fully-grown. Grubs will then burrow deep into the soil and rest through the winter.  The best treatment late in the season may kill only 60% of the grubs.  For most parts of the United States, treatments after late September are not very effective and are not recommended.

So don’t apply grub control too early in the spring or too late in the fall.  Note the directions on the package to not apply to very wet soils, but to water after application.  Since lawn soil tends to be very wet in the spring, and the grubs will not be laying their eggs until summer, applying grub control like GrubEx or Bayer Advanced, is not as effective as late May thru July applications.

If you are reading this and July is already past, you can still apply the product this year. It just is not that effective.  The general guideline is if there are adult Japanese beetles in your yard you should still apply the product.  For most lawns, getting good results for grub control means applying around May, June and early July, or when you see adult Japanese beetles flying around.

Grub control isn’t like killing other insects like ants or spiders.  It is a continual process and usually requires yearly applications.

Grub Control Near Me

Both Scotts Grubex and Bayer Advanced Season Long Grub Control work for Japanese beetles, Asiatic garden beetles, June beetles, European chafers,  Northern masked chafers,  Oriental beetles,  Southern masked chafers, Caterpillars,  Army worms, Cutworms and sod web worms.

Apply grub control according to the directions given on the bag. Then, water deeply enough so that it reaches the roots where the grubs are living. Don’t overwater. You don’t want to wash away the insecticide. Don’t water too little either.

Grubs are a serious problem for lawns in all regions. If you or a neighbor has ever had problems with grubs, it’s a good idea to put down an insecticide like GrubEx or Bayer Advanced as a precaution. Both products will also kill and help control sod webworms, armyworms, cutworms, crane fly larvae, Northern and Southern masked chafers, May/June beetle, black turfgrass Ataenius, green June beetle, annual bluegrass weevil, billbugs, Aphodius beetle, European chafer and Oriental beetle.

Scotts Grub-Ex Granular contains chlorantraniliprole 0.08%. Bayer Advanced Season Long Grub Control Granular contains imidacloprid 0.25%. Both are excellent products to control grubs.

Not Recommended:  Spectracide Triazicide Insect Killer Once and Done Granules.  Product contains gamma-cyhalothrin 0.05% and will not kill grubs. Works great on spiders, ants and other bugs but not on grubs.

Want to treat your lawn with an organic grub control?

Try an organic bacteria called Milky Spore Powder.  It’s available at Lowes and is an organic compound that contains bacteria that cause a natural disease of Japanese beetle grubs.

Milky spore controls Japanese Beetles, but it take 3-5 years for the organism to build up a high enough population in the soil and several applications must be made over this time. Once the milky spore population is high enough this product works well. You can start treatments in the fall, but you will not see effects for about three years.

Read more about milky spore here.

Victoria Stone

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