page_title: Black bean aphid
section_title: Description
hierarchical_section_title: Black bean aphid / Description
caption_attribution_description: English: Black Bean Aphids (Aphis fabae)
context_page_description: The black bean aphid is a small black insect in the genus Aphis, 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.
context_section_description: The black bean aphid is a small, soft-bodied (meaning that the exocuticle part of the exoskeleton is greatly reduced) insect that has specialised piercing and sucking mouthparts which are used to suck the juice from plants. This aphid is usually seen in large numbers and is a tiny, plump insect about two millimetres long with a small head and bulbous abdomen. The body is blackish or dark green in colour. Many adults are devoid of wings, a state known as aptery. Winged forms, known as alates, are longer and more slender than aptates and have shiny black heads and thoraxes. The membranous wings of the alates are held angled over the body. The antennae are less than two-thirds of the length of the body and both they and the legs are pale yellow in colour with black tips. The tibiae of the hind legs are swollen in egg-laying females. Near the rear of the abdomen is a pair of slender, elongated tubes known as cornicles or siphunculi. Their function is the production of a defensive waxy secretion. They are twice as long as the finger-like tail and both are brownish-black.
caption: Wingless aphids feeding on a stem
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