Description: Spotted alfalfa aphids are pale yellow-green in color with conspicuous rows of black spots on their backs. Each spot is tipped with a short spine. The winged form has smokey-colored areas along the wing veins. Mature aphids are only about 1/16-inch-long and one may need magnification to clearly see the spots.
Distribution: The spotted alfalfa aphid, Therioaphis maculata (Buckton), was introduced into central New Mexico in 1954. It has since spread throughout the alfalfa-growing areas of the United States.
Life History: Like many other aphids most individuals are wingless females that can produce living young without mating. Each female can give birth to 100 or more offspring. The spotted alfalfa aphid goes through four instars in as little as five days. The entire life cycle may be completed in less than seven days. In the fall, males can be produced which mate with oviparous (sexual form) females. The eggs that are laid from this sexual cycle are the overwintering stage.