Excerpts from the report Introduction: Pyrethrum mists and aerosols have been used extensively in tobacco warehouses and factories to control the tobacco moth and the cigarette beetle. They are highly effective against the moth, but much less so against the beetle. A pyrethrum mist, originally called a "space spray," was developed to control the tobacco moth in open-type storage warehouses. It did this most efficiently. Later, an effort was made to adapt this treatment to control the cigarette beetle in all types of warehouses and factories. This was much less successful. Many misconceptions have arisen as to what can be expected of mists and aerosols. This method of applying insecticides has certain inherent limitations. The object of this paper is to explain how, where, and why pyrethrum treatments are effective, and where and why they may not be effective.