How is pyrethrum obtained from members of the Asteraceae family?

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English daisies — Asterales True, or English, daisy (*Bellis perennis*).

Pyrethrum is obtained from specific members of the Asteraceae family—most notably Tanacetum coccineum and Chrysanthemum cinerariifolium—by harvesting and powdering their aromatic flower heads.1

These flower heads contain active substances known as pyrethrin, which function as contact poisons against insects and cold-blooded vertebrates. Because these natural powders are generally nontoxic to plants, birds, and mammals, they are widely utilized in household and livestock sprays, as well as in organic farming as a form of chemical control. While these plants were formerly classified under the genus Pyrethrum, they are now typically categorized within the genera Tanacetum or Chrysanthemum.1