Black bean aphid

The black bean aphid (Aphis fabae) is a small black insect in the Aphis genus, with a broad, soft body, a member of the order Hemiptera. Other common names include blackfly, bean aphid and beet leaf aphid. In the warmer months of the year it is found in large numbers on the undersides of leaves and on the growing tips of host plants, including various agricultural crops and many wild and ornamental plants. Both winged and wingless forms exist and at this time of year, they are all females. They suck sap from stems and leaves and cause distortion of the shoots, stunted plants, reduced yield and spoiled crops. This aphid also acts as a vector for viruses that cause plant disease and the honeydew it secretes may encourage the growth of sooty mould. It breeds profusely by live birth but its numbers are kept in check, especially in the later part of the summer, by various predatory and parasitic insects. Ants feed on the honeydew it produces and take active steps to remove the aphid's enemies. It is a widely distributed pest of agricultural crops and can be controlled by chemical or biological means. In the autumn, winged forms move to different host plants where both males and females are produced. These mate and the females lay eggs which overwinter.