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Black-Bean Aphids - Thomas Love

Aphis fabae is a true bug in the order Hemiptera. Common names include blackfly, black bean aphid, bean aphid and beet leaf aphid. It is a widely distributed pest of agricultural crops.


The insect is found throughout Western Europe, Asia, Africa, North and South America.


The black bean aphid is a true bug in the order Hemiptera. It has specialised piercing and sucking mouthparts, which are used to suck plant juices. It is a tiny insect about two millimetres long with a small head and bulbous abdomen. The body is blackish or dark green in colour and the membranous wings, when present, are held angled over the body. The legs and antenna are light yellow. The siphunculi are twice as long as the finger-like tail and both are brownish-black. There are two tube-like protrusions at the rear of the abdomen known as cornicles which are the openings of wax glands.


The eggs of the black bean aphid overwinter on certain host plants which include the spindle tree Euonymus europaeus, Viburnum andPhiladelphus. The aphids that hatch from these eggs in the spring are wingless females known as stem mothers. These are able to reproduceasexually giving birth to live offspring through a process known as parthenogenesis. The life span of the parthenogenetic female is about fifty days and during this period, each can produce as many as 30 young. The offspring are also females and able to reproduce without mating but the next generation to be produced are typically winged forms. These migrate to new host plants such as beans, sugar beet, docks and spinach. Further parthenogenesis on these hosts allows large populations of aphids to build up quickly. Winged and wingless forms are produced throughout the summer, the winged forms dispersing to new host plants. As autumn approaches, the winged forms migrate back to the primary hosts. Both males and sexual females are produced here, mating takes place and the females lay eggs which overwinter ready to repeat the life cycle the following year.

Host plants[]

The black bean aphid is found on sugar beet, beans, potatoes, sunflower and tomato. It colonises more than two hundred species of cultivated and wild plants. Among the latter it prefersPapaver somniferum, Arctium tomentonum, Chenopodium album, Atriplex rosea, Matricaria recutita and Cirsium arvense.