Bean Aphid

The bean aphid, also known as the black bean aphid, is a dark green to black, soft-bodied insect with a dark-colored head, antennae, and cornicles. The legs are black at the base and tips.

Bean aphid forms dense colonies on the undersides of celery leaflets. Winged bean aphids develop under conditions such as overcrowding and plant stress and disperse to other plants or fields.

Bean aphids can become a serious problem if not controlled or if their natural enemies have been negatively affected by pesticide applications. Bean aphids can number as high as several thousand per plant.

This pest can inflict three types of damage on the celery crop. First, it can stunt plant growth and reduce yields by consuming significant amounts of sap. Feeding by bean aphids may distort plant growth and development more than feeding by other aphid species. Second, it can transmit viral diseases such as celery mosaic, celery calico, and celery yellow spot. And finally, it can contaminate celery produce, particularly fresh market celery, with honeydew and debris; this contamination can lower the crop value.

Several parasitoid wasps provide natural control of aphids in celery, most notably species in the genera Diaeretiella and Lysiphlebus. In some cases, these parasitoids can eliminate high densities of aphids in a few weeks. Predators such as lady beetles, syrphids, and lacewings also attack aphids. Conserve the natural enemies by choosing selective insecticides and by providing habitat for parasites and predators to reproduce.

Destroy crop residue immediately after harvest. Avoid other aphid-favored crops such as lettuce and cole crops in adjacent, upwind fields. Intensify field monitoring when adjacent fields with aphid-favored crops are harvested.  Eliminating nearby weeds and woody shrubs that serve as host plants can reduce field infestations.

Biological controls, cultural controls, and sprays of narrow range oil (mineral oil) and insecticidal soaps (potassium salts of fatty acids) are acceptable to use in a certified organic crop.

Treatment thresholds for aphids on celery have not been established. Aphid survival and development are historically greatest during periods with temperatures that are less than 80°F. Bean aphid is more tolerant of hot temperatures than other aphid species, and therefore causes problems even in summer. Generally, bean aphids can be tolerated on young celery plants. On fresh market celery, infestations are more important when the petioles (stalks) start to form and when the rows begin to close. Infestations tend to be erratic in the field, so sample several locations. Sample intermediate-age stalks because this is where the most aphids are found. Concentrate on field edges, particularly where celery fields border harvested lettuce fields.