The spotted alfalfa aphid is a small, pale yellow or grayish aphid with four to six rows of spined black spots on its back.
Damage can also reduce the alfalfa's feed value.
A black fungus that grows on the honeydew excreted by the aphid reduces palatability. When selecting varieties, consult your farm advisor for information on varieties suited to your area. An introduced parasite, Trioxys complanatus, has become established on the spotted alfalfa aphid. Brown aphid mummies attached to leaves and stems of alfalfa plants indicate the presence of this parasite. Caution should be exercised in treating for aphids when the parasite is present.