Name: Rhopalosiphum padi
Alias: The bird cherry oat aphid can get up to 1/8 of an inch in size, which is slightly larger than most aphids. Its color can range from dark green to orange, and can often have several colors throughout its body. Like most aphids it has cornicles, which are often referred to as the “tailpipes” coming out the back end. They reproduce quickly, having anywhere from 2 to 10 generations in a single growing year. Winged males are rarely seen, appearing at the end of the growing season. Females lay their eggs on fruit trees such as cherries so the young nymphs can feed on the new growth before moving on to cereal grains later in the growing season.
Crimes: Bird cherry oat aphids prefer cereal grain crops, such as wheat, barley and oats. Bird cherry oat aphids can cause significant yield to crops in large populations, although their numbers never become large enough to raise concern in Eastern Idaho. Their biggest crime is they are known to spread diseases, such as Barley Yellow Dwarf Virus.
Redeeming qualities: None.
Sentence: The average population is controlled from natural predators already present in Idaho and control is rarely merited. Populations can spike if predators are eliminated from a pesticide application and there are no other aphid species present. No economic thresholds exist for Idaho, however if more than 50 aphids are present on each stem of cereal grain, you will want to consider applying an insecticide. Be sure to read and follow label instructions.