Bénassy, C., Bianchi, H., & Milaire, H.G. 1971 La temperature, facteur previsionnel du cycle evolutif de Prospaltella perniciosi Tow. [Temperature, a factor supplying a forecast of the developmental cycle of Prospaltella perniciosi Tow.]. Entomophaga 16: 4, 411-420.

Notes: Prospaltella perniciosi Tower has now been widely released in orchards in Europe for the control of Quadraspidiotus perniciosus (Comst.), and wherever the parasite has 3-4 generations a year, as compared with the two generations a year of the scale in the areas most seriously affected, it affords good control. However, the delay before the parasite is seen effectively to reduce the host population is determined by climatic factors, as well as by the stage of the host available at the time of release. Studies had shown that the threshold of development for Prospaltella is about 10 deg C, and the mean number of day-degrees necessary for the development of the parasite has been calculated to be 397.22. The accuracy of estimates of the number of parasite generations in a given area, based on these calculations, is illustrated by reference to data from field studies in various countries between 1959 and 1970.