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Pyrethrins and Pyrethroids: You Know Their Differences?

Safe-Killer takes pride in creating a comprehensive range of insect control products, primarily based on pyrethroids, as well as other active ingredients. A frequent inquiry we receive is, “What distinguishes pyrethrins from pyrethroids?”

Numerous “py-words” exist, including pyrethrum, pyrethrins, permethrin, and pyrethroids. As a result, let’s break it all down:

  • Pyrethrum and pyrethrins are insecticides that are extracted from specific species of flowers belonging to the chrysanthemum family.
  • Pyrethrins are the six active molecules or esters that function as the lethal agent in the extract.
  • Pyrethrum represents the entire extract from the flowers, whereas pyrethrins denote the purified six esters.
  • Pyrethroids are artificial compounds created to replicate the impact of the pyrethrin esters.
  • Pyrethroids typically contain fewer chemical variations, usually consisting of a single synthetic molecule, in contrast to the six esters present in pyrethrum.
  • Pyrethrins are effective against a wide range of insects, while pyrethroids generally have more extended residual effects and greater stability during storage.


The natural pyrethrins are composed of six active ester molecules: Pyrethrins I and II, Jasmolin I and II, and Cinerin I and II. The proportion of these molecules in the pyrethrum extract may vary with each harvest of the flower and can be affected by environmental factors such as temperature, humidity, and rainfall.

The insecticidal properties of pyrethrins have been utilized for a long time. However, they are vulnerable to degradation due to UV exposure and offer shorter residual control. Nonetheless, they cause a “flushing” behavior in targeted insects.



Pyrethroids are synthetic compounds that have been developed to mimic the effects of natural pyrethrins, but typically contain only one synthetic molecule that mimics a single ester found in pyrethrins.

Pyrethroids are synthetically produced molecules that have a more consistent chemical composition compared to the naturally occurring pyrethrins in pyrethrum. As a result, they do not induce the same “flushing” behavior in target insects. Pyrethroids also tend to provide longer residual control as they are more resistant to degradation by UV light than pyrethrins.

A Different Viewpoint

Each time pyrethrum is harvested, the concentration of the 6 esters, which are the killing agents, in the extract varies. This is similar to how a cup of coffee or a glass of wine tastes different depending on where the coffee bean or grape was grown due to environmental conditions.

As previously mentioned, synthetic pyrethroids have a consistent chemical composition every time they are produced, similar to how a well-known soda brand tastes the same no matter where it is consumed. However, due to the lack of variation in synthetic pyrethroids, insects may develop resistance to them more rapidly than to pyrethrins.

Please go to Safe-Killer to learn more about our Insect Repellents and Pest Control Equipment or Contact Us for more information about your purchase.

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