Severin, H.C. 1920 Enforcement of the nursery inspection law of South Dakota.. Eleventh Annual Report of the State Entomologist of South Dakota for the Period Ending June 30, 1030 8-10.

Notes: Scales listed among the principal pests attacking nursery stock for the year include Chionaspis americana, C. salicis-nigrae, Pulvinaria vitis, Lecanium corni, Lepidosaphes ulmi and Aspidiotus ancylus.