Good Sunday evening and

Thank you for your question. It has been assigned to me. I will try to help you.

This is the time of the year (late May, early June) that white grubs appear close to the upper regions of soil. This is very natural and occurs in most lawns. Most likely they are either Japanese beetle grubs or May/June bugs. For me to answer your question, please provide the following background information:

1). In past years have you noticed any defoliation of your trees or shrubs? Related to this, in past seasons have you had any reason to suspect the presence of grubs.?

2). In the picture that you provided showing the grubs, what was the approximate area of the turf under which you found them?  The reason why I am asking this is to ascertain the severity of the problem. As a rough rule of thumb, unless 10 or less grubs are under a square foot of turf, there is not a grub problem.

Many thanks for your anticipated response. Thanks for consulting our forum.

Thanks for getting back to us.

It certainly appears that white grubs are visiting your yard. These are Scarab larvae and often are just called “white grubs”. Usually the adults are May bugs, June bugs, and Japanese beetles. See:

https://extension.umn.edu/corn-pest-management/white-grubs - larvae-1191610

https://hort.extension.wisc.edu/articles/mayjune-beetles/

There are two windows in which effective grub control can be done: early June as grubs move towards upper regions of the turf and late July/early August as newly born grubs are also near the surface. At these two times chemical interventions are possible. See the following for further information:

https://extension.umn.edu/news/white-grub-control-lawns

https://extension.umn.edu/yard-and-garden-insects/japanese-beetles

https://extension.umn.edu/yard-and-garden-insects/japanese-beetles - when-to-manage%3A-start-early%21-1591110

https://ipm.missouri.edu/MEG/2018/1/organic_management_japanese_beetle/

https://www.thespruce.com/controlling-adult-japanese-beetles-1402495

Bottom line: Timing is the most important part of grub control. As I described, you have two windows for treatments. For maximum effectiveness, two grub treatments should be done in each window, separated by two weeks.

Good luck. Please get back to us if you have further questions. Thanks for consulting us.

Thanks for getting back to us.

The dates you mentioned sound good but recognize that dealing with white grubs can be a moving target. In early summer, as well as later in the summer, these grubs are in the higher levels of the soil under your grass. In this state and location, they are most susceptible to insecticide intervention. My suggestion of two treatments at both times is an attempt to deal with the continual movements of the grubs. Trying to get rid of them is rarely a “one shot deal”.

As a volunteer Master Gardener of the University of Minnesota, I cannot recommend any specific commercial product. Having said that, in one of the links I previously sent to you, the following was stated:

“The best timing is during the month or so before the adult beetles first emerge and start laying eggs (mid-June to mid-July in Minnesota). Chlorantraniliprole (such as Scott's Grub-Ex) is an effective, preventative insecticide that is also low risk for bees.

Products containing imidacloprid or clothianidin are also effective if applied preventively, but they can pose a hazard to bees foraging on flowering weeds or nesting in treated lawns.”

These products can be purchased at any gardening center or big-box store. There should be no need to online ordering.

Good luck. Glad to be of assistance. Thanks for consulting us.

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