Soares, A.O., Elias, R.B., & Schanderl, H. 1999 Population dynamics of Icerya purchasi Maskell (Hom; Margarodidae) and Rodolia cardinalis Mulsant (Col; Coccinellidae) in two citrus orchards of Sao Miguel island (Azores).. Boletín de Sanidad Vegetal, Plagas 25(4): 459-467.

Notes: Two citrus orchards in the North of São Miguel island (Rabo de Peixe) were selected in order to evaluate the population dynamics of Icerya purchasi and Rodolia cardinalis. For that purpose sixteen trees were sampled from May to November 1997 and from April to October 1998. I. purchasi develops 2 annual generations, one at the end of spring and the other in autumn. Young females are the most abundant stage during the winter. The larval stages of the predator appear mainly at the beginning of summer and adults start to appear in July reaching the peak of abundance at the end of that season. This maximum probably contributes to the decrease of I. purchasi density during the summer reaching its minimum at the end of this season. During autumn the population level of Rodolia beetle decreases coinciding with the second generation of I. purchasi. After November no individuals were found on trees probably indicating the beginning of the hibernation period. The majority of larvae and young females of the scale were found on the leaves and mature females were found on the branches, indicating a migration within plant parts.