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Black bean aphid

Aphis fabae[4]

The black bean aphid is a small, dark aphid that forms dense colonies on the shoot tips, leaves and flowers of beans, nasturtiums and many other plants, overwintering on shrubs such as euonymus and viburnum.[1][2][3]

Group
Insect
Order
Hemiptera
Family
Aphididae
US records
20 states
Sources
4 cited
Updated
2026-10-19

No licensed photo of this species is available yet; the identification notes below describe what to look for.

On this page
  1. Identification
  2. Where it lives
  3. Biology
  4. Damage and signs
  5. Health risk
  6. Control
  7. Related profiles
  8. Common questions
  9. Sources

How to identify it

  • Wingless adults are about 1/16 to 1/8 inch (1.5 to 3 mm) long, pear-shaped, black to dark olive green, often with faint waxy stripes; winged adults are very dark.[1][2]
  • They feed in tight clusters on shoot tips, young leaves and flower stems.[1][2]
  • Infested leaves curl or deform and get sticky with honeydew, which draws ants and grows black sooty mold.[1]

Where it lives

It is found on garden and field plants in North America and Europe; WSU in Washington, the Connecticut station and the UK's AHDB all describe it.[1][3][2]

US map: public records from 20 states since 1990 (GBIF).

Biology and life cycle

Eggs spend the winter on shrubs such as euonymus (spindle tree) and viburnum; in spring the aphids move to summer hosts, including beans, many vegetables, flowers and ornamentals.[1][2]

Colonies can build up very quickly in warm, humid summer weather.[2]

Damage and signs

  • Heavy feeding curls and deforms new growth; on beans it damages flowers, slows or stops pod development and makes plants wilt in dry weather.[1][2]
  • It can also spread several plant viruses to beans and beets.[2]

Health risk

It feeds only on plants; WSU, AHDB and the Connecticut station mention no risk to people.[1][2][3]

Control

Prevention

Avoid excess nitrogen fertilizer, which boosts aphid reproduction.[1]

Biological control

Lady beetles, lacewings, syrphid fly larvae and parasitic wasps are important natural enemies; avoid broad-spectrum insecticides that kill them, and control ants that guard the colonies.[1][3]

Pesticides

Where colonies get out of hand, insecticidal soap sprayed directly on the aphids is one option the Connecticut station lists.[3]

Common questions

What are the clusters of tiny black bugs on my bean and nasturtium tips?
Most likely black bean aphids, which crowd shoot tips and new leaves in summer.[1][3]
Where do black bean aphids come from each year?
They overwinter as eggs on shrubs like euonymus and viburnum, then fly to beans and other summer hosts.[1][2]

Sources

  1. Washington State University Extension, “Bean: Bean aphids (HortSense).” hortsense.cahnrs.wsu.edu/?p=2262 (accessed 2026-10-19)
  2. Agriculture and Horticulture Development Board (UK), “Management of the black bean aphid in field beans and sugar beet.” ahdb.org.uk/knowledge-library/management-of-the-black-bean-aphid-in-field-beans-and-sugar-beet (accessed 2026-10-19)
  3. Connecticut Agricultural Experiment Station, “Plant Pest Handbook: Nasturtium (Tropaeolum).” portal.ct.gov/caes/plant-pest-handbook/pphn/nasturtium-tropaeolum (accessed 2026-10-19)
  4. iNaturalist, “Aphis fabae taxon page (order and family).” www.inaturalist.org/taxa/1584763 (accessed 2026-10-06)

Updated 2026-10-19. Built from sourced records. Spot an error? Tell us.