pyrethrum

/paɪˈriːθrəm/
noun
  1. A type of chrysanthemum plant whose flowers are used to make natural insecticides.
    • Gardeners often grow pyrethrum near vegetables to repel harmful insects.
    • The dried and powdered pyrethrum flowers are used in organic pest control.
    • Pyrethrum plants have white and yellow daisy-like flowers.
  2. An insecticide made from the dried flowers of the pyrethrum plant.
    • Pyrethrum has been used for centuries to control lice and fleas.
    • This spray contains pyrethrum and is safe for use around pets.
    • The farmer applied pyrethrum to the tomato plants to kill whiteflies.