Plan the perfect garden with our interactive tool →

Pyrethrin Vs. Permethrin

Pair of daisies in bloom outdoors
NA/Photos.com/Getty Images

More than 150 years ago people of central Eurasia were using dried, crushed, daisy-like flowers from the genus Chrysanthemum to treat body lice. They were onto something. The crushed powder, called pyrethrum, contains components, called pyrethrins, which have an almost immediate paralyzing affect on insects. Pyrethroids are, essentially, man-made versions of pyrethrins. Permethrin is one of those man-made copies of the natural insecticide.

Natural Pyrethrin

Two species of chrysanthemum flowers, C. cinerariaefolium and C. cineum, provide the pyrethrins for the commercial production of insecticides. Used in indoor and outdoor bug foggers, head lice treatments and flea sprays, pyrethrins are one of the least toxic treatments for pest insects around the home and garden. They are, however, highly toxic to aquatic life and to beneficial insects, such as bees. Commercial use of pyrethrins is limited since they break down quickly when exposed to light or water. Researchers have developed synthetic pyrethroids to create longer lasting pesticides.

Synthetic Permethrin

A synthetic pyrethroid, known as permethrin, was registered for use on cotton in 1979. Since then, it has become one of the most widely used pyrethroids in the United States, available for agricultural and home garden use against a broad spectrum of insect pests. Unlike the botanically derived pyrethrins, permethrin persist longer in the environment, continuing its insecticidal properties for up to 12 weeks. Like its natural counterpart, permethrin is highly toxic to aquatic creatures and bees.

Insecticide Action

Sodium channels in nerve cell membranes allow charged atoms, ions, to pass through, changing the electrical charge of the cell, which releases neurotransmitters. Neurotransmitters communicate, through electrical messages, with other nerve cells to produce an action, such as moving a leg or flying away. In insects, pyrethrin and permethrin interfere with that communication by allowing the ion channels to stay open longer, ultimately paralyzing the insect. Since it does not degrade as quickly as natural pyrethrin, permethrin also acts as a gut poison to insects that eat permethrin-treated plants.

Toxic Effects

Both the natural and synthetic versions of chrysanthemum based insecticides threaten fish, mollusks, amphibians and non-target insects. Despite this risk, pyrethrins and permethrins are widely used because they break down quickly in the environment and have few toxic effects on mammals and birds. In 2013, the U.S. Environmental Protection Agency instituted labeling initiatives for manufacturers of pyrethrins and permethrin to ensure that professional and residential users apply the products in ways that minimize run-off and contamination to water bodies. Read and follow those instructions when applying and storing these insecticides.

Related Articles

Pyrethrum Daisy as a Pesticide
Pyrethrum Daisy as a Pesticide
Types of Insecticide
Types of Insecticide
Components of Insecticide
Components of Insecticide
Caffeine As an Insecticide
Caffeine As an Insecticide
Natural Alternatives to Sevin in the Garden
Natural Alternatives to Sevin in the Garden
Dawn As an Insecticide for Gardens
Dawn As an Insecticide for Gardens
Safe Insecticides for Tomato Plants
Safe Insecticides for Tomato Plants
Is Wasp Spray Safe for Plants?
Is Wasp Spray Safe for Plants?
Cygon for Fruit Trees
Cygon for Fruit Trees
Will Diazinon Kill Ants?
Will Diazinon Kill Ants?
Is Roundup Safe Around Chickens?
Is Roundup Safe Around Chickens?
The Derris Insecticide
The Derris Insecticide
Is Preen Dangerous to Dogs?
Is Preen Dangerous to Dogs?
The Best Insecticide for Caterpillars
The Best Insecticide for Caterpillars
Garden Guides
×