Jannone, G. 1967 Biocenologia coccidica su agrumi e pittosporo in Liguria e conseguenze del controllo di Rodolia cardinalis su Pericerya purchasi in rapporto alla espansione areale di Pulvinaria floccifera.. Entomologica 3: 88-128.

Notes: Title in English: [Coccid biocenology on Citrus and Pittosporum in Liguria and the consequence of control by Rodolia cardinalis of Pericerya purchasi in this report on the increased distribution of Pulvinaria floccifera.] When R. cardinalis has successfully eradicated Pericerya purchasi populations, Pulvinaria floccifera arrives to take its place. P. floccifera is not a host for R. cardinalis and, therefore, has required mechanical or chemical control. The population of R. cardinalis consequently decreases, occasionally even disappearing. The author suggests breeding R. cardinalis in order to have stock on hand in case of future attacks, and to attempt a biological equilibrium.