By: Organic Gardener | February 3, 2016
Making pyrethrum sprays and dusts
Traditionally, dried ground flowers from pyrethrum (Tanacetum cinerariifolium) have been used to make dusts and sprays at home. When making or using these dusts always wear gloves, goggles and a mask over the nose and mouth.
Finely grind the dried flowers in a pestle and mortar until they become powder and sprinkle over infested plants.
Cockroach bait recipe
Sprinkle a tablespoon of pyrethrum dust into a margarine container with half a cup of red wine. Pour some cooking oil over the top and place as a trap for cockroaches. Keep it out of the reach of children and pets.
Coarsely grind the dried flower heads and to every firmly packed half-cup of flowers, add 1L of warm water. Cover and leave to stand for three hours, strain and add a teaspoon of pure soap and one of cooking oil. Shake well before use. Don't spray in temperatures over 32°C. The spray will kill bees so use it when they are not active—in the early morning or evening. This spray will only remain potent for about 12-24 hours so any that is not used should be discarded after this time. Remember that even though this is an organic spray it will also kill beneficial insects so only use as a last resort.
Although relatively harmless to people, pyrethrum is still a poison so baits, dust and sprays need to be carefully labeled and stored out of the reach of children and pets. The flowers and dust will maintain their potency longer if stored in the fridge.