Misting the pyrethrum based solution provides both population reduction and repulsion. When an insect comes in contact with a droplet of the solution it has an immediate effect termed activation. It stimulates the insects' nervous system and causes them to fly or move erratically, flushing them out of their hiding places, and increasing the probability of them contacting a lethal dose of the mist. Knock down and death are rapid which effectively reduces the population immediately with each application. Insects detecting small residual amounts of Pyrethrum will avoid or leave the area. In addition, female mosquitoes experience what's known as jamming, which blocks their natural appetite for blood. Tests demonstrated a bare arm exposed to a population of mosquitoes would be bitten repeatedly. But when the same population is exposed to small amounts of Pyrethrum, the arm is not bitten, due to their feeding mechanism being "Jammed".
Pyrethrum insecticides have become the natural solution to an age old problem due to their effectiveness, low toxicity to mammals, and biodegradability. What makes them even more attractive is the fact that no known insect population has become resistant to it, even after decades of use.
More about Pyrethrum: Pyrethrum refers to several Old World plants of the genus Chrysanthemum (e.g., C. coccineum) which are cultivated as ornamentals for their showy flower heads. It is also the name of a natural insecticide made from the dried flower heads of C. cinerariifolium and C. coccineum. Pyrethrum was used for centuries as an insecticide and as a lice remedy ("Persian Insect Powder," "Persian Pellitory") in the Middle East. It was sold worldwide under the brand Zacherlin by Austrian industrialist J. Zacherl.
C. cinerariifolium looks more like the common daisy than other pyrethrums. Its flowers, typically white with a yellow center, grow from numerous fairly rigid stems. Plants have blue-green leaves and grow to between 45 to 60 cm in height. The plant is economically important as a natural source of insecticide. The flowers are pulverized and the active components called pyrethrins, contained in the seed cases, are extracted in the form of an oleoresin. This is applied as a suspension in water or oil, or as a powder. Pyrethrins attack the nervous systems of all insects, and inhibit female mosquitoes from biting. When not present in amounts fatal to insects, they still have an insect repellent effect. They are harmful to fish, but are far less toxic to mammals and birds than many synthetic insecticides and are non-persistent, being biodegradable and also breaking down easily on exposure to light. They are considered to be among the safest insecticides for use around food. Kenya produced 90% (over 6,000 tons) of the world's pyrethrum in 1998. Production in Tanzania, Ecuador and Austrialia is also significant. Source: Wikipedia 4/20/2009. abridged.
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