Permethrin 13.3% concentrate is mixed at a rate of 2⅔ to 5½ fluid ounces per gallon of water for most pest control applications. The exact amount depends on what you’re treating and which pests you’re targeting. Below you’ll find the specific ratios for common uses, from general pest control around your home to tick treatment in your yard and livestock applications.
General Pest Control Around Structures
For routine pest control around the exterior and interior perimeter of a building, mix 2⅔ fluid ounces of permethrin 13.3% per gallon of water. This is the standard low-end rate and works for common crawling insects like ants, spiders, cockroaches, and earwigs. Apply the solution as a coarse spray along baseboards, door frames, window frames, and the foundation perimeter of your home.
If you’re dealing with heavier infestations, you can increase the concentration up to 5½ ounces per gallon. Starting at the lower rate makes sense for maintenance spraying, while the higher end is better suited for knockdown of active infestations or pests that are harder to control.
Tick and Mosquito Yard Treatment
For ticks in your yard, the mixing range is 2⅔ to 5½ fluid ounces per gallon of water. Ticks tend to concentrate in shaded, leafy areas at the edges of lawns, along fence lines, and in tall grass. Focus your spray on those transition zones rather than open, sunny lawn. Mosquito treatment uses a similar range, with the spray applied to shrubs, ground cover, and shaded resting areas where mosquitoes harbor during the day.
Coverage rate matters as much as the mix ratio. Most labels call for applying enough finished solution to wet the vegetation and ground surface without heavy runoff. For a typical backyard perimeter and landscape bed treatment, plan on roughly one gallon of mixed solution per 1,000 square feet, though dense vegetation may require more.
Quick-Reference Mixing Chart
- General pest control (ants, spiders, roaches): 2⅔ oz per gallon of water
- Ticks (yard and perimeter): 2⅔ to 5½ oz per gallon of water
- Mosquitoes (yard foliage spray): 2⅔ to 5½ oz per gallon of water
- Heavy infestations or hard-to-kill pests: up to 5½ oz per gallon of water
These rates are based on the 13.3% permethrin formulation specifically. If you have a different concentration (such as 10%, 36.8%, or 38%), the ounces per gallon will be different. Always check that the percentage on your bottle matches before using these numbers.
Scaling Up for Larger Volumes
If you’re using a backpack sprayer or mixing in a larger tank, multiply accordingly. For the standard 2⅔ oz per gallon rate:
- 2 gallons: 5⅓ oz
- 3 gallons: 8 oz
- 5 gallons: 13⅓ oz
- 10 gallons: 26⅔ oz
For the high rate of 5½ oz per gallon:
- 2 gallons: 11 oz
- 3 gallons: 16½ oz
- 5 gallons: 27½ oz
- 10 gallons: 55 oz
Fill your sprayer about halfway with water first, add the concentrate, then top off with the remaining water. This helps distribute the product evenly without excessive foaming.
Livestock and Poultry Applications
Permethrin 13.3% is also labeled for use on livestock, but the dilution rates differ from premise spraying and vary by animal species and pest. For cattle treated with permethrin sprays targeting horn flies, face flies, lice, and ticks, application typically involves 1 to 2 quarts of coarse spray per animal applied over the whole body. The specific dilution depends on the concentration you’re starting with, so follow the livestock section of your product label rather than using the premise spray rates above.
For poultry mite and lice control, permethrin is applied as a fine mist at roughly half an ounce of diluted spray per bird, or about one gallon of finished solution per 100 birds. Spray should also be directed at roosts, walls, nesting boxes, and cages where mites hide between feedings.
How Long the Treatment Lasts
Permethrin leaves a residual layer that continues killing insects after it dries. On indoor surfaces exposed to daylight, about 60% of the permethrin remains active after 20 days. Outdoors the residual is shorter because UV light and rain break it down faster. On plant foliage, the half-life ranges from one to three weeks depending on the plant species and sun exposure.
For most outdoor yard treatments, plan on reapplying every 2 to 4 weeks during peak pest season. Indoor perimeter treatments typically hold longer since they’re protected from weather, but high-traffic areas and surfaces that get cleaned regularly will lose effectiveness sooner.
Safety Around Cats
Cats are extremely sensitive to permethrin. Their livers lack the enzyme that breaks down this chemical, so even small exposures can cause tremors, seizures, and death. Never apply permethrin products directly to cats, and keep cats away from treated surfaces until the spray has fully dried. If you spray indoors, ventilate the area and do not allow cats back into treated rooms until surfaces are completely dry to the touch. If you treat a dog with a permethrin-based flea product, keep the dog separated from any cats in the household until the product has dried.
When mixing and applying, wear chemical-resistant gloves and long sleeves. Avoid spraying near fish ponds, streams, or other water features, as permethrin is highly toxic to fish and aquatic invertebrates.