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Pyrethrins/Pyrethrum are natural insecticides produced by certain Chrysanthemum species of plants. In contrast, Permethrin (‘per-meth-rin’) is a synthetic, man-made insecticide, whose chemical structure is based on natural pyrethrum. Pyrethrum was first recognised as having insecticidal properties around 1800 in Asia and was used to kill ticks and various insects such as fleas and mosquitoes. Six individual chemicals have active insecticidal properties in the pyrethrum extract, and these compounds are called pyrethrins. Pyrethrum are viscous, tan-coloured brown resins, liquids, or solids which inactivate readily in air. Pyrethrum are soluble in organic solvents such as alcohol, kerosene, nitromethane, petroleum ether, carbon tetrachloride, and ethylene dichloride. A quick acting liquid insecticide especially suited for control of insect pests of vegetables, ornamentals, and exotic crops. The piperonyl butoxide ingredient is used to enhance the activity of the permethrin (synergist).
Pyrethrum has been used effectively to control insects for decades and is nonpersistent, decomposing rapidly in the environment. This rapid degradation of pyrethrum has resulted in little known cases of insect resistance, making it an excellent choice for the control of agricultural pests, control of insects on pets and/or livestock. Pyrethrum powder is toxic to ants, roaches, silverfish, bed bugs, fleas, wasps, spiders, crickets, mosquitoes, and just about every other category of unwanted house or garden pest. Because it decomposes rapidly in the environment, pyrethrum has been approved for a wide range of indoor and outdoor uses, including homes, restaurants, broad-scale spraying operations, and organic farms.
Pyrethrins break down quickly in the environment, especially when exposed to natural sunlight. Pyrethroids are manufactured chemicals that are very similar in structure to the pyrethrins, but are often more toxic to insects, as well as to mammals, and last longer in the environment than pyrethrins. Pyrethrins and pyrethroids are often combined commercially with other chemicals called synergists, which enhance the insecticidal activity of the pyrethrins and pyrethroids. The synergists prevent some enzymes from breaking down the pyrethrins and pyrethroids, thus increasing their toxicity. Technical-grade (concentrated) pyrethrins and pyrethroids are usually mixed with carriers or solvents to produce a commercial-grade formulated product.

Household insecticide (flies, mosquitoes, gar- den insects, etc.).

The six insecticidal constituents of the extract of the pyrethrum flowers Pyrethrum (Chrysanthemum cinerariaefolium). Pyrethrins I and II are most prominent, existing in the ratio 71:21:7 for pyrethrin (I and II), cinerin (I and II), jasmolin (I and II). Pyrethrins are potent, nonsystemic, contact insec_x0002_ticides, causing rapid paralysis or knockdown and death at a later stage in a variety of insects. They exhibit low vertebrate toxicity with an acute oral LD50 in rats of 1.2 g/kg. The mechanism of action involves modification of nerve membrane Na1 channels. Opening and closing of the Na1 channel is slowed, resulting in increased Na1 permeability and depolarization leading to hyperexcitability. Symptoms in humans include gastrointestinal irritation, nausea, vomiting, diarrhea, numbness of tongue and lips, syncope, hyperexcitability, incoordination, convulsions, muscular paralysis, collapse and death due to respiratory paralysis. Treatment involves gastric lavage, emetics, cathartics, demulcents, artificial respiration if necessary and short-acting barbiturates for convulsions.