The label is the law. Read your product's label before you mix or apply; the rates here come from the labels listed under Sources.
- Active ingredient
- Spores of Paenibacillus popilliae (labeled as Bacillus popilliae)
- Chemical class
- A soil-inhabiting bacterium that causes milky spore disease in grubs.[3]
- Mode of action
- Bacterial disease: grubs swallow the spores while feeding, the bacterium kills them, and dead grubs release more spores into the soil; Paenibacillus popilliae is not named in the IRAC classification[3][6]
- Signal words
- Milky Spore Powder: Caution[1]
Milky Spore Granular: Caution[2]
What university trials have found
University of Minnesota Extension notes that milky spore bacteria occur naturally in soil and may infect a small percentage of grubs, and says applying commercial milky spore products has not been shown to provide any benefit in modern university research trials.[4]
Clemson Extension calls milky spore disease the most common and widely used biological control for grubs, but adds that, as with all biological controls, results can vary widely with the site and its conditions.[3]
Building up spores in the soil
The powder label treats spots 4 feet apart and leaves the ground between them to become inoculated naturally. It says uniform, highly efficient control can't be expected until the entire area has been inoculated.[1]
The granular label calls for applications in spring, summer and fall for two successive years to reach the greatest buildup of spores in the soil.[2]
Grubs it doesn't control
The bacteria in these products infect only Japanese beetle grubs, according to University of Minnesota Extension, so they won't help with lawns where the grubs are masked chafers or other species.[4]
Ohio State recommends against milky disease products for masked chafers, whose grubs aren't affected by the Japanese beetle strain.[5]
Where it is used
Grubs take in the bacterium during normal feeding. It kills them, and as a dead grub dries out it releases more bacterial spores into the soil.[3]
Milky Spore Powder is labeled for Japanese beetle grubs in lawns and other grassy areas around homes, ornamental gardens and flower beds, and mulched and ground cover beds, applied by the teaspoon in a grid of spots or mixed into fertilizer for a drop spreader.[1]
Milky Spore Granular goes on with a broadcast applicator or drop spreader at 20 pounds per 7,000 square feet. For the greatest buildup of spores in the soil and the best grub control, its label calls for applications in spring, summer and fall for two years in a row.[2]
The commercial product uses the Japanese beetle strain. Masked chafer grubs have their own strain of milky disease, which occurs naturally in Ohio but usually infects less than 20 to 25% of a population, and Ohio State says the Japanese beetle strain has no effect on masked chafers, so milky disease products aren't recommended for them.[5]
Products and registrations
Label rates
| Product | Use | Pests | Rate |
|---|---|---|---|
| Milky Spore Powder | Lawns, grassy areas, flower beds, mulched and ground cover beds (spot application) | Japanese beetle grubs | 2.5 lb per 10,000 sq ft[1] One level measuring teaspoon in spots every 4 ft along rows 4 ft apart: 10 oz treats 2,500 sq ft, 1 lb treats 4,000 sq ft, 2.5 lb treats 10,000 sq ft, and 10 lb treats an acre. Any season when the ground is not frozen; water lightly afterward. |
| Milky Spore Granular | Lawns and other listed areas (broadcast applicator or drop spreader) | Japanese beetle grubs | 20 lb per 7,000 sq ft[2] 1 lb per 350 sq ft (20 lb per 7,000 sq ft) by broadcast applicator or drop spreader, in spring, summer and fall for two successive years. |
How to apply it, step by step
1. Protective gear
- The signal word is CAUTION: harmful if inhaled or absorbed through skin, and it causes moderate eye irritation. Avoid breathing the dust and avoid contact with skin, eyes or clothing.[1]
- Wash thoroughly with soap and water after handling and before eating, drinking, chewing gum, using tobacco or using the toilet. Take off and wash contaminated clothing before wearing it again.[1]
2. Before you spray
- The label is for Japanese beetle grubs in lawns and other grassy areas around homes, ornamental gardens and flower beds, and mulched and ground cover beds.[1]
- Pick calm weather when heavy rain isn't predicted for the next 24 hours, so wind or rain doesn't blow or wash the powder off the treatment area. Any season works as long as the ground isn't frozen.[1]
- Shake the container to fluff the powder before using it, because it settles during shipping.[1]
3. Mixing
- For spot treatments there's nothing to mix: the powder goes on as it comes. If you'd rather use a drop spreader on lawns and other grassy areas, the label lets you mix it thoroughly with a granular lawn fertilizer, using the fertilizer amount for your lawn and twice the amount of milky spore powder the spot method calls for on the same area, so the spores end up concentrated enough to start and keep an infection going.[1]
4. Applying
- Put one level measuring teaspoon of powder on top of the grass, or on the ground between plants, in spots every 4 feet along rows 4 feet apart. That's 10 ounces for 2,500 square feet, 1 pound for 4,000 square feet, 2.5 pounds for 10,000 square feet, or 10 pounds per acre.[1]
- A Milky Spore Dispenser Tube can be used instead, following the directions that come with it.[1]
- Water lightly after applying to soak the spores into the soil.[1]
5. After you spray
- Sweep any powder that lands on a driveway, sidewalk or street back onto the treated lawn or garden, to keep it from running off into water or drains.[1]
- The areas between treated spots are left to become inoculated naturally. The label says uniform, highly efficient control can't be expected until the whole area has been inoculated.[1]
First aid
- If inhaled: move the person to fresh air. If the person isn't breathing, call 911 or an ambulance, then give artificial respiration, and call a poison control center or doctor for treatment advice.[1]
- If on skin or clothing: take off contaminated clothing, rinse skin immediately with plenty of water for 15 to 20 minutes, and call a poison control center or doctor for treatment advice.[1]
- If in eyes: hold the eye open and rinse slowly and gently with water for 15 to 20 minutes. Remove contact lenses after the first 5 minutes, then keep rinsing. Call a poison control center or doctor for treatment advice.[1]
- Have the container or label with you when you call. The label's hotline is 1-800-801-0061, Monday through Friday, 9 a.m. to 5 p.m. Eastern; at other times call a poison control center at 1-800-222-1222.[1]
Storage, spills and disposal
- Store it in a cool, dry place away from direct sunlight, with the container tightly closed to keep moisture out. Don't contaminate water, food or feed by storage or disposal.[1]
- Don't reuse or refill the container. Put an empty one in the trash or recycle it where available. For a partly filled container, call your local solid waste agency for disposal instructions, and never put unused product down any indoor or outdoor drain.[1]
Safety and environmental hazards
People
Both labels carry the signal word CAUTION and say the product is harmful if inhaled or absorbed through skin. The powder label also says it causes moderate eye irritation, and to avoid breathing the dust and to avoid contact with skin, eyes or clothing.[1][2]
Pets
The powder label lists its precautions as hazards to humans and domestic animals together and gives no separate pet warning. Clemson Extension describes milky spore disease as nontoxic to non-target species in the lawn.[1][3]
Bees and pollinators
University of Minnesota Extension says the bacteria infect only Japanese beetle grubs and have no effect on beneficial organisms. Neither label carries a bee warning.[4][1][2]
Fish and water
Neither label gives a fish or aquatic toxicity statement. Both say not to let the product enter or run off into storm drains, drainage ditches, gutters or surface waters, and to apply it in calm weather when heavy rain isn't expected within 24 hours.[1][2]
Common questions
- Does milky spore actually work?
- University of Minnesota Extension says applying commercial milky spore products has not been shown to provide any benefit in modern university research trials, and Clemson Extension says results vary widely with the site and conditions.[4][3]
- Will milky spore kill other lawn grubs?
- No. University of Minnesota Extension says the bacteria infect only Japanese beetle grubs, and Ohio State says the commercial Japanese beetle strain has no effect on masked chafer grubs.[4][5]
- How much milky spore powder do I need?
- The label calls for one level teaspoon in spots every 4 feet along rows 4 feet apart: 10 ounces for 2,500 square feet, 1 pound for 4,000 square feet, 2.5 pounds for 10,000 square feet, or 10 pounds per acre.[1]
- When can milky spore go down?
- Any season, as long as the ground isn't frozen. Water lightly afterward to soak the spores into the soil, and avoid days with heavy rain expected in the next 24 hours.[1]
- Is it safe around pets and pollinators?
- The label's CAUTION statement covers humans and domestic animals: harmful if inhaled or absorbed through skin, with moderate eye irritation. University of Minnesota Extension says the bacteria have no effect on beneficial organisms, and Clemson calls the disease nontoxic to non-target species in the lawn.[1][4][3]
Sources
- U.S. EPA Pesticide Product Label System, “Milky Spore Powder label, EPA Reg. No. 63191-1 (EPA-stamped, April 22, 2010).” www3.epa.gov/pesticides/chem_search/ppls/063191-00001-20100422.pdf (accessed 2026-11-08)
- U.S. EPA Pesticide Product Label System, “Milky Spore Granular label, EPA Reg. No. 63191-16 (EPA-stamped, February 17, 2011).” www3.epa.gov/pesticides/chem_search/ppls/063191-00016-20110217.pdf (accessed 2026-11-08)
- Clemson Cooperative Extension Home & Garden Information Center, “White Grub Management in Turfgrass, HGIC 2156 (updated August 24, 2022).” hgic.clemson.edu/factsheet/white-grub-management-in-turfgrass/ (accessed 2026-11-08)
- University of Minnesota Extension, “Japanese beetles (reviewed 2025).” extension.umn.edu/garden-and-home/yard-and-garden/yard-and-garden-insects/japanese-beetles (accessed 2026-11-08)
- Ohio State University Extension, “Masked Chafers, ENT-51.” ohioline.osu.edu/factsheet/ENT-51 (accessed 2026-11-08)
- Insecticide Resistance Action Committee, “IRAC Mode of Action Classification Scheme, Version 11.5 (Feb. 2026).” irac-online.org/documents/moa-classification/ (accessed 2026-11-08)