Good Morning,
Milky spore disease is a population suppressant. The goal when using milky spore disease is to keep Japanese beetle levels below damaging thresholds (10 to 12 grubs per square foot). However, the use of milky spore disease is not without problems or concerns. First, it can be very difficult to determine results because other microorganisms (for example, predators and pathogens) in the soil may kill Japanese beetle grubs more rapidly than milky spore. Second, milky spore affects only one species of white grubs; and, in some situations, the Japanese beetle may not be the only or the predominant species. Third, results may take several seasons, 3 to 5 years in cooler climates, so several years may lapse before adequate control of grubs is achieved. Furthermore, populations of the pathogen may not increase quickly enough to retard the spread of an isolated colony of grubs. Finally, the use of milky spore may be cost prohibitive compared with other currently available pest control materials.

See attached for grub control.

Milky Spore Disease (illinois.edu)
How to choose and when to apply grub control products for your lawn - Turf (msu.edu)
Smart lawn care to protect pollinators - Gardening in Michigan (msu.edu)
White Grub Management in Turfgrass | Home & Garden Information Center (clemson.edu)

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