Black Bean Aphid

• In spring and summer the females reproduce without males and give birth directly to live females, which in turn already carry the next generation inside them: three generations nested one within another, like Russian dolls.
• It alternates host plants with the season: it overwinters as an egg on spindle or viburnum and in spring flies to broad beans, beet or thistles.
• Ants tend it, carry it and defend it from ladybirds and hoverflies in exchange for its honeydew — herding in the fullest sense.
• Its cycle alternates generations: sexual in autumn on the winter host shrub, where it lays its eggs, and several parthenogenetic, live-bearing generations in summer on herbaceous plants.
• Ants tend and milk it: they collect its honeydew, rich in sugars and amino acids, and in return defend it and even carry young aphids to fresh plants.
• The quantity and composition of the honeydew change with the plant it feeds on, and that determines how closely the ants attend it.
• It is in fact a complex of at least four subspecies that share the same winter hosts but prefer different summer plants.

Skeleton type

Invertebrate - chitin exoskeleton (insect)

Habitat and environment

Broad beans, beet, thistles and other herbaceous plants; overwinters on spindle and viburnum

Sexual maturity

The nymphs moult four times before reaching adulthood

Litter / clutch size

Viviparous reproduction by parthenogenesis through the summer: each founding female gives birth to up to 30 live nymphs; the sexual generation in autumn lays overwintering eggs on spindle (Euonymus europaeus)

Sources consulted: Wikipedia (es): Aphis fabae · Koppert, ficha Black bean aphid · ficha de especie de Aphis fabae · ScienceDirect (Hughes 1989) · Science Advances, How colonial animals evolve · Wikipedia, Zooid · Koppert

Best time: Very large colonies in the warm months on shoots and the underside of leaves; in autumn the winged forms migrate back to the primary host