Bt galleriae (grubGONE!) for lawn grubs
University results disagree, so do not count on it. In Kentucky, granular Btg failed to control early- or late-stage Japanese beetle grubs under several turfgrasses at several field sites (Redmond and colleagues, 2020). Minnesota Extension calls recent university results inconsistent. Purdue is more positive: it says the product works on small and large grubs alike, with control of 35–100% depending on the grub species. Count grubs before treating. The grub nematode Heterorhabditis bacteriophora is the other biological option Purdue and Minnesota Extension list, though Minnesota says its results also vary.
Before you order
A strain of Bt that makes a toxin active against scarab beetles. Sprayed on leaves (beetleGONE!), it cut Japanese beetle feeding for 3–14 days in Kentucky trials. As lawn granules (grubGONE!), university results range from failure to good control. It kills monarch caterpillars, so keep it off milkweed. How it works, how to tell it has established and the supplier list are on the full Bacillus thuringiensis subsp. galleriae strain SDS-502 profile.
Other controls for white grubs
- Heterorhabditis bacteriophoraNematode · 250k–500k /m² (1–2 billion per acre) for Japanese and Oriental beetle grubs; BASF gives European chafer 0.5–1 million /m²
- Ground beetlesWild predator · wild, attract it
- Rove beetlesWild predator · wild, attract it