Milky Spore (Paenibacillus popilliae)
Quick Facts
- Type
- Microbial
- Source
- Bacterial pathogen naturally targeting Japanese beetle grubs
- OMRI Listed
- Yes ✓
- Bee Safe
- Yes
- Pet Safe
- Yes
- Residual
- 10-20+ years once established in soil; self-reproducing
- Best For
- Long-term Japanese beetle grub suppression in lawns. Set-and-forget biological control.
What Is Milky Spore (Paenibacillus popilliae)?
Grubs ingest bacterial spores while feeding in soil. Bacteria multiply in the grub's blood (hemolymph), turning it milky white, eventually killing the grub and releasing billions of new spores into the soil. Self-perpetuating once established.
Source: Bacterial pathogen naturally targeting Japanese beetle grubs
What Pests Does Milky Spore (Paenibacillus popilliae) Kill?
Milky Spore (Paenibacillus popilliae) is effective against the following pests:
How to Apply Milky Spore (Paenibacillus popilliae)
Best for: Long-term Japanese beetle grub suppression in lawns. Set-and-forget biological control.
Avoid for: Immediate grub problems. Other grub species (June beetles, chafers). Cold climates (zone 4 and below).
Residual activity: 10-20+ years once established in soil; self-reproducing
Safety Profile
| Category | Rating |
|---|---|
| Bee Safety | 🟢 Safe for bees |
| Pet Safety | 🟢 Safe for pets |
| Overall Rating | Safe — Safe for kids, pets, and bees when used as directed |
Why Isn't Milky Spore (Paenibacillus popilliae) Working?
If Milky Spore (Paenibacillus popilliae) isn't delivering results, check these common failure modes:
Very slow establishment — takes 2-4 years to build effective spore density
Japanese beetle-specific — does not control other grub species
Soil temperature dependent — needs 60-70°F soil temps for grub activity
Cold climates reduce effectiveness below USDA zone 5
Best Milky Spore (Paenibacillus popilliae) Products
St. Gabriel Milky Spore Powder
PowderClassic application — teaspoon drops every 4 feet
St. Gabriel Milky Spore Granular
GranulesEasier spread application