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How to Manage Pests

Pesticide Information

Active ingredient: Pyrethrin

Pesticide type: insecticide (botanical)

Synonyms: pyrethrins; pyrethrum

See example products below.

Potential Hazard1 to
Water quality2
(aquatic wildlife)
Natural enemies
Honey bees3 People and Other Mammals
Acute4 Long Term5
Not listed

Acute Toxicity to People and Other Mammals4

  • Toxicity rating: Slightly Toxic

Long-Term Toxicity to People and Other Mammals5

  • On US EPA list: Not listed;
  • On CA Proposition 65 list: Not listed

Water Quality Rating2

  • Absorbed runoff toxicity risk to fish rating: Low
  • Solution runoff toxicity risk to fish rating: High
  • Source: UC IPM WaterTox Database (originally NRCS Pesticide Properties Database)

Impact on Natural Enemies

  • Overall toxicity rating: Moderate
  • Specific impacts: predatory mites (No information), parasitoids (Moderate), general predators (Moderate)

Impact on Honey Bees3

  • Toxicity category: III - Apply only during late evening, night, or early morning

Pests for which it is mentioned in Pest Notes

AntsAphidsBagrada BugBed BugsBrown Marmorated Stink BugCalifornia OakwormClothes MothsConenose BugsElm Leaf BeetleEye GnatsFliesFungus GnatsHackberry Woolly AphidHead LiceLace BugsLawn insectsLeaffooted BugSpidersThripsWidow Spiders and Their Relatives

Application Tips

Pyrethrins rapidly break down after application. They must be applied when target pests are present. Pyrethrins are fast acting and cause rapid knockdown of flying insects or temporary paralysis of other insects. They are used to flush out cockroaches, for instance, from hiding places in homes. Insects may recover from application of pyrethrins alone and to be most effective, they need to be combined with the synergist piperonyl butoxide. Formulations that include insecticidal soap or other insecticides may increase effectiveness.

Precautions and Safety Equipment

Minimize your exposure to pesticides.  Avoid contact with eyes.  Wear eye protection, long pants, a long-sleeved shirt, and a hat that can be washed after each use.  Always read label of individual product for additional directions.

Always check the label before purchasing or applying a pesticide product for a specific pest on a specific plant to be sure it can be applied. Follow label directions precisely.


Example home, garden or landscape use products6

Doktor Doom Spider Mite Knock Out Insecticide Plant Spray for Tomatoes and vegetables • Doktor Doom Total Release Fogger • Earth-Tone Insect Control • Enforcer Flea & Tick Spray for Dogs II • Garden Tech Worry Free Brand RTU Dust • Gardentech Worry Free Brand Concentrate • Gardentech Worry Free Brand RTU • Pyganic Livestock and Poultry Insecticide • Spider Killer3


  1. Potential Hazard Rating: VL=Very low, L=Low, LM=Low to Moderate, M=Moderate, LH=Low to High, MH=Moderate to High, H=High, VH=Very High, N=None, NKR=No Known Risk, —=No data
  2. Water quality ratings from Pesticide Choice: Best Management Practice (BMP) for Protecting Surface Water Quality in Agriculture, ANR Publication 8161, or the USDA-NRCS WIN-PST database—see Pesticides: Water-Related Toxicology of Active Ingredients.
  3. Honey bee ratings are: (Very High) I-Do not apply to blooming plants; (High) II-Apply only during late evening; (Moderate) III-Apply only during late evening, night, or early morning; and (Low) IV-Apply at any time with reasonable safety to bees. For more information, see How to Reduce Bee Poisoning From Pesticides (PDF), Pacific Northwest Extension Publication PNW591.
  4. Acute oral toxicity ratings for people and other mammals based on LD50 and US EPA Acute Toxicity Ratings system: H = Highly Toxic (LD50 <50), M = Moderately Toxic (LD50: 50-500), L = Slightly Toxic (LD50: 500-5000), VL = Not Acutely Toxic (LD50 >5000)
  5. Long term ratings indicate whether the active ingredient is on the California Prop 65 list, which indicates if materials are known to cause cancer or reproductive toxicity, or whether the US EPA has classified the pesticide as "likely to be carcinogenic to humans", "Group B-Probably Human Carcinogen", or "Group C-Possible Human Carcinogen."
  6. These products were registered for home and garden use in California in July 2013. Professional use products are not included. If no example products are listed, this active ingredient may be available only for professional use. Individual products are registered for specific uses on specific sites. Read the label to determine if the product is registered for your use. Note that some products may be formulated with additional pesticides.

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Statewide IPM Program, Agriculture and Natural Resources, University of California
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