Coquillett, D.W. 1891a Report on various methods for destroying scale insects. Letter of submittal.. Bulletin (United States Department of Agriculture) 23: 19-26.

Notes: Control of the California red scale with Hydrocyanic gas. First description (p. 29) of Aspidiotus citrinus. Other species mentioned include Aspidiotus aurantii and Icerya purchasi.