In short pyrethrum is a simple daisy with a rare natural property. It is nature’s own insecticide.
The pyrethrum daisy or Chrysanthemum cinerariifolium, is a remarkable plant. Packed into microscopic oil bearing glands on the surface of the seed case within the flower’s head is a complex plant oil – a combination of six organic esters – which the plant has evolved to keep insects away.
Pyrethrum today is grown in many countries and its oil extract can be used in many forms. From the simple mosquito coil to household aerosols to foggers and sprays. The natural insecticide is remarkable in that it is fast acting against insect pests, yet breaks down quickly in UV light, leaving no residue in the environment.
Because of this non-persistence, pyrethrum does not enter food chains, as has been the case with some synthetic insecticides, and no real insect resistance occurs. Crucially, although pyrethrum acts as a nerve agent on insect pests, quickly knocking them down and killing them, it is relatively non-toxic to humans and warm-blooded animals.