Milky spore for Japanese beetle grubs
Documented because it is the product sold for this pest, not because it works well. The commercial strain infects Japanese beetle grubs only. In multi-year Kentucky trials, commercial spore powder did not raise milky disease levels or reduce grub numbers, and Minnesota Extension says modern trials have shown no benefit. Even on its own terms it is slow: the label says control cannot be expected until the whole lawn is inoculated. It does nothing for beetles already feeding on roses.
Before you order
A powder of bacterial spores spotted onto the lawn and watered in. Japanese beetle grubs that eat the spores can develop fatal milky disease. It does not affect any other lawn grub, and in university trials the commercial products gave poor control. How it works, how to tell it has established and the supplier list are on the full Paenibacillus popilliae profile.
Other controls for japanese beetle
- Heterorhabditis bacteriophoraNematode · 250k–500k /m²; BASF: 25–50 million per 1,000 ft² of turf
- Ground beetlesWild predator · wild, attract it
- Rove beetlesWild predator · wild, attract it
- Bacillus thuringiensis subsp. galleriae strain SDS-502Microbial beetle control · Maker's rate — beetleGONE! 2–4 oz per gallon of water, sprayed on foliage where beetles are feeding