Neuffer, G. 1975 Zur Situation in den Befallsgebieten der San-Jose-Schildlaus (Quadraspidiotus perniciosus Comst.) in Baden-Wurttemberg nach zwanzig Jehren Freilassungen von Prospaltella perniciosi Tow.. Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz 82(8/9): 503-514.

Notes: Title in English: [The situation in areas attacked by the San Jose scale (Quadraspidiotus perniciosus Comst.) in Baden-Wurttemberg twenty years after releasing Prospaltella perniciosi Tow.] Prospaltella perniciosi Tower, an endoparasite of the orchard pest Quadraspidiotus perniciosus (Comst.), was first introduced from the United States into West Germany in 1950. During 1954 to 1974, 27 million examples of the Aphelinid were released for the control of the scale insect in the Baden-Wurttemberg area of West Germany. The parasite became successfully established (eventually colonising different European climatic zones), the average rate of parasitism in the Baden-Wurttemberg area being 34-43%; infestation by Q. perniciosus on apple and currant decreased by more than 90% between 1959 and 1974.