Quayle, H.J. 1927 Spray and fumigation combination for resistant red scale.. Journal of Economic Entomology 20: 667-673.

Notes: Results are given of spray alone, fumigation alone, and a combination of these against the red scale on citrus trees. Highest efficiency was secured when fumigation followed within a week or ten days the application of oil spray. Oil shown to absorb little if any HCN gas and an oil spray serves as a protective film to the citrus tree, rendering it less susceptible to hydrocyanic acid injury.