Folgerungen aus dem Auftreten der Gallen von Dreyfusia nordmannianae Eckst. (=D. nüsslini CB.) in Mitteleuropa auf ihren Generationszyklus

On the paracycles of Dreyfusia nordmannianae Eckst. in Central Europe . Evidence is produced showing the paracycle of D. nordmannianae (= D. nüsslini) on European silver fir is capable of producing both males and females. This is contrary to at least one opinion that adelgids on the secondary host can produce only females.