🧪 Active Ingredient Profile

Milky Spore Disease

Biological Control Agent

Milky spore is a naturally occurring soil bacterium that specifically targets Japanese beetle grubs. Once established, it persists in the soil for 15-20 years, providing long-term grub suppression without repeated application. It's the ultimate set-it-and-forget-it biological control.

🧪
Classification
Biological Control Agent
EPA Signal Word
N/A
Mode of Action
Bacterial infection: spores ingested by grub → multiply in blood → kill grub → release billions more spores
⚖️ Educational use only. Always read and follow the full product label — the label is the law under FIFRA. Full disclaimer → | ⚗️ Mixing Calculator →

🎯 Target Pests

Japanese beetle grubs (Popillia japonica) ONLY. Does NOT control other grub species (June bugs, chafers, masked chafers). This is extremely species-specific. If your grub problem is not Japanese beetles, use beneficial nematodes instead.

🏷️ Common Products & Brand Names

St. Gabriel Organics Milky Spore Powder, Milky Spore Granular (Gabriel), Gabriel Milky Spore Lawn Spreader Mix. Limited product selection because only one company has scaled production.

⚠️ Safety & Precautions

Completely non-toxic to humans, pets, wildlife, earthworms, beneficial insects, and all plants. Cannot affect anything except Japanese beetle grubs. USDA/EPA exempt from registration requirements. OMRI organic approved.

✅ 20-year protection: Once milky spore establishes in your soil, it continues killing Japanese beetle grubs for 15-20 years without reapplication. The grubs actually spread the disease by dying and releasing more spores.
Example
0.5 oz
per gallon
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💡 Pro Tips & Best Practices

Application: Apply in fall when grubs are actively feeding (September-October in most areas). Place 1 teaspoon of powder every 4 feet in a grid pattern. Water in lightly. Takes 2-3 years to fully establish throughout the lawn.

Patience required: Unlike chemical grub treatments, milky spore takes 1-3 years to build up enough in the soil to provide effective control. But once established, it lasts decades. Plan accordingly.

Temperature requirement: Soil temperature must be above 65°F for spores to activate. This is why fall application works well — grubs are feeding and soil is still warm.

Combine with nematodes: For immediate grub relief while milky spore establishes, apply beneficial nematodes (Heterorhabditis) in the same season. Nematodes provide fast knockdown; milky spore provides long-term control.

🐛 Pests This Treats — Learn More

Click any pest to view its full identification guide, biology, and treatment options.

🐛 Ants → 🐛 Grubs → 🐛 Japanese Beetle → 🐛 Scales → 🐛 Ticks →

🌿 Environmental & Ecological Impact

🐝 Bees / PollinatorsNONE
🐟 Fish / Aquatic LifeNONE
🐦 BirdsNONE
🐕 Mammals / PetsNONE
🦐 Aquatic InvertebratesNONE
💡 Targets only Japanese beetle grubs. Completely non-toxic to all non-target organisms. Persists in soil 10+ years.

❓ Frequently Asked Questions

Q: Is milky spore safe for pets?
Follow the product label. Keep pets out of treated areas until completely dried (2–4 hours for sprays). Once dry, treated surfaces pose minimal risk to dogs and cats.
Q: Can I use milky spore indoors?
Check the specific product label — formulations vary. Baits and dusts often have indoor labeling; concentrates and granulars are typically outdoor.
Q: How long does milky spore last after application?
Residual varies by formulation, surface type, weather, and UV exposure. Indoor applications last longer than outdoor. Check the product label for re-application intervals.
Q: What should I do if exposed?
Remove contaminated clothing, wash skin with soap and water. For eye contact, rinse 15–20 minutes. For ingestion or severe symptoms, call Poison Control (1-800-222-1222). Have the product label available.

📋 Safety Data Sheet (SDS)

📋

Milky Spore Disease — Safety Data Sheet

View the official SDS document for this product directly on the CDMS label database.

📄 View SDS on CDMS → 🏛 Search EPA Label Database →
Milky Spore Disease Safety Data Sheet page 1
📄 Milky Spore Disease — Safety Data Sheet · View the complete SDS document above or download below
📄 CDMS Label & SDS Database 📄 EPA Label Search
💡 Did you know? Milky spore was discovered in 1933 by researchers studying a mysterious disease killing Japanese beetle grubs in New Jersey. The USDA mass-produced it during WWII as an agricultural defense measure. It's been protecting American lawns for over 80 years.
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Reviewed by Derek GiordanoContent reviewed by a licensed pest management professional. Last reviewed: April 2026.
📚 Sources: EPA Pesticide Labels · NPIC Pesticide Info
Published: Jan 1, 2025 · Updated: Apr 7, 2026