A shoot of common ivy (Hedera helix) infested with ivy aphids (Aphis hederae). The picture shows the extending tip of a shoot that was growing against a wall, taken in Spring (May, UK). The aphids (deep purple-brown) feed by ingesting sap from the soft tissues of the growing plant. The majority of the insects in the picture are wingless females (aptera). They are reproducing parthenogenetically at this season. Unlike many aphids, A. hederae does not alternate its host. It feeds on ivy throughout the year, although it may also be found occasionally on houseplants, since in late summer, winged forms are produced (alates). In sheltered situations, such as against a wall, parthenogenetic reproduction may continue throughout the winter.