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Giant Willow Aphid

Tuberolachnus salignus[4]

The giant willow aphid is one of the largest aphids, forming dense colonies on the bark of willow twigs and stems in late summer and fall.[1][2][3]

Group
Insect
Order
Hemiptera
Family
Aphididae
US records
24 states
Sources
4 cited
Updated
2026-10-17
Giant willow aphid, a large spotted aphid, on a willow stem
Giant willow aphid, a large spotted aphid, on a willow stem. (c) Joss Carr, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0
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

  • Adults are about 1/4 inch (5 to 5.8 mm) long, with rows of black spots and a raised, shark-fin-like cone in the middle of the back.[1][2][3]
  • NC State describes them as gray; UMass as medium to dark brown with fine hairs that give a grayish-golden sheen.[1][2]
  • Antennae are short, about half the body length or less.[1][2]

Where it lives

Reported on willows in North Carolina, Massachusetts and the Pacific Northwest.[1][2][3]

US map: public records from 24 states since 1990 (GBIF).

Biology and life cycle

All are females that reproduce without mating; no males have been found, and each aphid can produce about 30 young.[1][2]

Colonies appear by midsummer, peak in late summer or fall and can persist on the bark into February; where they spend late winter to midsummer is not known.[1][2]

In the PNW, colonies often concentrate on bark close to the ground.[3]

Damage and signs

  • It feeds mainly on willow and sometimes on poplar, covering 1- to 3-year-old twigs in heavy years.[1][2]
  • Damage is usually minimal, but colonies drip large amounts of honeydew that grows black sooty mold and draws stinging insects.[1][2][3]

Health risk

None to people or pets, though the honeydew attracts stinging insects.[1]

Control

Traps and physical control

Prune out heavily infested twigs when numbers are low, or knock aphids off with a strong stream of water.[1]

Biological control

NC State notes parasitic wasps, lady beetles, hover fly larvae, lacewings and an aphid-killing fungus reduce colonies in warm weather, while UMass reports natural enemies are rare.[1][2]

Pesticides

For organic control NC State suggests insecticidal soap or horticultural oil, which also helps weather away sooty mold.[2]

Common questions

What are the huge aphids covering my willow branches?
Most likely giant willow aphids, one of the largest aphids, common in late summer and fall.[1][2]
Do giant willow aphids hurt willows?
Usually not much; the honeydew and sooty mold are the main nuisance.[1][2][3]

Sources

  1. UMass Extension Landscape, Nursery and Urban Forestry Program (Landscape Insect & Mite Guide), “Tuberolachnus salignus (Giant Willow Aphid).” www.umass.edu/agriculture-food-environment/landscape/publications-resources/insect-mite-guide/tuberolachnus-salignus (accessed 2026-10-16)
  2. NC State Extension, “Giant Willow Aphid (PDIC Factsheet, revised May 11, 2021).” content.ces.ncsu.edu/giant-willow-aphid (accessed 2026-10-16)
  3. Pacific Northwest Insect Management Handbook (Oregon State, Washington State, University of Idaho), “Willow (Salix)-Aphid (Hosts and Pests of Landscape Plants).” pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/willow-salix-aphid (accessed 2026-10-16)
  4. iNaturalist, “Tuberolachnus salignus taxon page (order and family).” www.inaturalist.org/taxa/354036 (accessed 2026-10-06)

Updated 2026-10-17. Built from sourced records. Spot an error? Tell us.