It is a true bug and sucks sap from leguminous plants, particularly alfalfa (known as lucerne in most countries outside North America).

It is very similar in appearance to the closely related pea aphid (Acyrthosiphon pisum), but is often a more bluish shade of green.

[2] Hot summer weather, with temperatures averaging above 80.8 °F (27.1 °C), favours the plants' natural resistance mechanisms, and numbers of aphids reduce sharply.

Wingless forms are prolific and may have twelve or more generations in a season, producing young at the rate of seven nymphs per day.

Where infection rates are high, yellowing, twisting, stunting and leaf drop may occur, young seedlings may die and plants regrowing after cutting are severely affected.