Fig. 3 in Identification guide to Nordic aphids associated with mosses, horsetails and ferns (Bryophyta, Equisetophyta, Polypodiophyta) (Insecta, Hemiptera, Aphidoidea)

Fig. 3. Dioecious one-year holocycle (Rhopalosiphum padi). The inner zone represents the primary host (bird cherry, Prunus padus and allies), the outer zone the secondary (usually graminoids). The fundatrix gives birth to apterae, which in turn give birth to alatae, most of which migrate to the secondary hosts. In autumn males and gynoparae (viviparae giving birth to oviparae) migrate to the primary host, where mating and egg-laying take place. A small fraction of the viviparae may remain on the primary host