Further refinement of a technique for testing contact insecticides.

Drosophila melanogaster were treated with nicotine sulphate solution by both intermittent and continuous spraying methods. There was no clearly demonstrated superiority of one method over the other. An analysis of variance performed on observed mortalities expressed as angles of equal information indicated that increasing age of flies, increasing numbers of flies per cage, longer delays between filling of the cages and spraying, and increased proportions of males in the samples, raised observed mortalities significantly. The type of cloth used to cover the cages must be standardized. Data on fly ages and numbers of flies per cage were also put through the probit analysis of Bliss which indicated flies aged 5 days to be most susceptible and fly numbers to affect equally the mortalities due to all concentrations