TOXICITY • E-FREE TRANSLATION.COM • Definition of Toxicity

... pyrethrum flowers are now generally available commercially, and these give fairly good results in the destruction of house flies in buildings. Most of the sprays of pyrethrum extract contain kerosene oil as a carrier, and undoubtedly the kerosene has much to do with the toxicity of the spray. Such materials are most applicable to buildings which become infested with flies and which can be readily closed up at night and the air within thoroughly saturated with the spray by means ...

— The House Fly and How to Suppress It - U. S. Department of Agriculture Farmers' Bulletin No. 1408 • L. O. Howard and F. C. Bishopp