Klett, W. 1953 Beitrag zum Auftreten und zur Lebensweise von Aspidiotus perniciosus Comst. [Contribution to the occurence and behavior of Aspidiotus perniciosus Comst.]. Gesunde Pflanzen 7: 152-154.

Notes: From the initial discovery in southwestern Germany seven years ago, Quadraspidiotus perniciosus has spread throughout Germany. The distribution is somewhat dependent on the climate that is ideal for plum trees, and outside of this climate it poses little threat. Chemical and biological control are discussed and natural enemies listed.