Aphid, Black Bean
In the garden: Viburnum, dahlia, nasturtium and a number of ornamental garden plants
On Crops: Bean, beet, celery and many other vegetable garden plants
Europe and isolated areas where celery is grown commercially
These are dark green to dark gray soft-bodied insects about two millimeters long. They are often found in dense clusters on tender new growth.
Black bean aphids are usually visible on plants because of their contrasting color. Aphids feed by sucking plant juices, so infested growth is often yellowed and curled. In addition to the direct damage aphid feeding does to plants, aphids can transmit several diseases.
Check plants often for early outbreaks. Clip off and compost stems holding aphid clusters. Encourage beneficial insects including lady beetles, syrphid flies, and lacewings, which are important aphid predators.
In small outbreaks, a high pressure spray from the garden hose can help remove aphids from plants. Follow up with two applications of insecticidal soap, one week apart. Be sure to apply the soap spray to leaf undersides and crevices.
Lady beetles and their larvae are great beneficial insects to welcome into your garden. Ants tend to be attracted to the honeydew left by aphids, so ant activity can often lead you to aphid colonies.