B, Young nymph.
C, Older nymph.
They reproduce by giving live birth to more females, without mating. Chrysanthemum aphids overwinter in greenhouses where they feed throughout the winter. During the warmer mounts they leave the greenhouses in search of new plants. They also may be moved about as plants are shipped or sold. When the winged female stage infests new plants, it usually starts feeding and producing live nymphs. Each female can produce four to eight young aphids per day.
Within about a week the new nymphs mature into wingless females which begin to bear young of their own. One aphid on a plant in a short time may build the population up to hundreds of individuals . As the plant becomes crowded, more and more of the offspring develop into winged females which in turn migrate to other plants to begin new infestations.
Infested plants in the greenhouse should be sprayed thoroughly when aphids are first noticed. On outdoor plantings natural enemies my control minor infestations. For specific chemical controls, see your county Extension agent or consult your state's pest management guide for the control of pests on ornamental plants.