5. pyrethrum, one ounce to four gallons of water; or, better still, mixed one part with about twenty parts of flour and applied while the dew is on, is an effectual remedy.
"The Cauliflower"
A. A. Crozier
Every dwelling in Colon and Panama was thoroughly fumigated with pyrethrum powder or with sulphur, and then cleared of dust and refuse, which, with the insensible but not always dead mosquitoes, was then burnt.
"The Panama Canal and its Makers"
Vaughan Cornish
Instead, use pyrethrum or insect powder, which may be diluted by mixing with cheap flour-one ounce of insect powder to five of flour.
"Ontario Teachers' Manuals: Nature Study"
Ontario Ministry of Education