Pyrethrum is a viscous liquid that is barely soluble in water. It is a natural insecticide that is obtained from the dried blooms of chrysanthemum species. In former times, the pulverized blooms were marketed in various commercial forms. Montenegrin or Dalmatian insect powder was obtained from Tanacetum cinerariifolium (synonyms: Chrysanthemum cinerariifolium and Pyrethrum cinerariifolium) and Armenian, Persian or Caucasian insect powder from Tanacetum coccineum (synonyms: Chrysanthemum coccineum, Pyrethrum roseum and Pyrethrum carneum). Pyrethrum contains a mixture of insecticidal components, pyrethrin I and pyrethrin II, jasmolin I and jasmolin II and cinerin I and cinerin II. Together, they are called pyrethrins. Today, the active insecticidal components are extracted. Pyrethrin I is the most effective insecticide; it is about 100 times more effective than the other components. Pyrethrin II has the most rapid anaesthetic effect.
The Pyrethrin Joint Venture conducted studies on all toxicologically relevant end points using a pyrethrum extract that was produced by 3 manufacturers from typical pyrethrum products and contained 57.6% active components (Schoenig 1995). However, it is assumed that different pyrethrum extracts contain different amounts of pyrethrins, cinerins and jasmolins, which may lead to differences in the severity of the insecticidal and toxic effects.