Spotted Alfalfa Aphid,Therioaphis maculata (Buckton)

PLANTS ATTACKED: Alfalfa and bur clover.

DESCRIPTION: The female aphid is about l/16 inch long, is pale yellowish green and has on its back four to six rows of black spots bearing spines. Both winged and wingless forms occur. The wings have smoky areas along the veins. The aphid jumps readily when disturbed.

LIFE HISTORY: Activity and reproduction of this insect are more or less continuous throughout the year. Infestations are greatest during the late winter and spring. A female gives birth to 25 to 100 young which mature in approximately 1 week. The adult lives about 1 month. There may be many generations annually, the rate of reproduction depending on weather conditions. This insect generally is more active during dry weather and amid mild temperature.

DAMAGE: Spotted alfalfa aphids suck the juices from leaves and tender stems. They inject a toxin that interferes with the growth of the plant. Damaged leaves curl, turn yellow and usually drop off of the plant. Shedding of the lower leaves usually occurs first. Severely damaged plants are almost defoliated. Young and old alfalfa stands are greatly reduced and in some cases almost destroyed. These insects also excrete honeydew in which sooty molds grow. Alfalfa with heavy deposits of honeydew and sooty molds cannot be dehydrated properly, and it is difficult to cut and bale the crop.