Bean aphid (Aphis fabae)
Green peach aphid (Myzus persicae)
Leafcurl plum aphid (Brachycaudus helichrysi)
Pest description and damage The aphids tend to be small (.0625 to 0.125 inch in length), oval to pear-shaped, soft-bodied insects with piercing-sucking mouthparts. Color varies between species. Bean aphid is a dull black gregarious aphid; green peach aphid is yellowish green with dark lines; and the leafcurl plum aphid has both green and reddish forms. Aphids tend to feed in colonies and are found on the most succulent plant tissues. Feeding damage is usually minor but can compromise the vigor of the host if aphid populations are high. Aphids produce honeydew that encourages growth of a black sooty mold. Some aphids, such as the green peach aphid, are vectors of plant diseases, particularly viruses. Damage ranges from yellowing and shriveling of leaves to severely and tightly curled leaves, or mottled yellowing of virus symptoms.
For biology, life history, monitoring and management
See "Aphid" in:
Management-chemical control
See Table 1 in:
Chemical Control of Landscape Pests
For more information
Pappu, Hanu. Sam Smith Endowment: Virus diseases of dahlias. Washington State University. http://dahlia.wsu.edu/