Most aphids are green, yellow or pink in colour. Those found in field crops may be one of these colours or white, bronze, dark-brown or black. Sometimes, the wingless form is green whereas the winged form of the same species is black. The antennae are usually quite long. Aphids can be distinguished from similar insects by examining their 'tail' ends.
Aphids bear a pair of tubes at the tips of their abdomens that resemble tiny exhaust pipes.
These tubes are called 'cornicles'. Also, aphids tend to move very slowly compared to insects that are similar in appearance. A greenish-blue aphid, this species has short, broad cornicles with a dark spot surrounding their base. It is usually about 3 mm long. It is found in colonies on stems and upper leaves of barley and corn, secreting much sticky honeydew.