White grubs are the larvae of various beetles, with June and Japanese beetles being common in Minnesota. 
Check the severity of the infestation. To do this, you can cut out 1- to 2-foot squares of sod in damaged areas and examine the root zone for grubs. If you find an average of 3-5 grubs per square foot, treatment may be necessary.

Chemical Treatments: If you opt for insecticides, consider products containing imidacloprid or chlorantraniliprole, which are effective against grubs. Timing is crucial; treatments should ideally be applied at or before the egg hatch, which typically occurs in midsummer.

Beneficial Nematodes: These microscopic roundworms can be effective against white grubs when applied during their active feeding stages, usually late spring to early fall. Make sure the soil temperature is between 60°F and 90°F for the best results. Effectiveness can vary based on conditions, so monitor carefully 

Cultural Practices: Maintaining a healthy lawn can mitigate damage. This includes proper watering and mowing practices, which can help the turf withstand the stress caused by grubs.

Natural Predators: Encourage beneficial insects or wildlife that feed on grubs. However, be mindful that animals like skunks or raccoons could cause additional damage while searching for grubs.  See also:
https://extension.entm.purdue.edu/publications/E-271/E-271.html