Pest profile

Woolly Hackberry Aphid

Shivaphis celti · Hemiptera: Aphididae[2]

Woolly hackberry aphids make a sticky mess of honeydew and sooty mold under hackberry trees, but years of infestation don't seriously harm the trees.[1]

Fuzzy white wax-covered woolly hackberry aphid on a leaf
Fuzzy white wax-covered woolly hackberry aphid on a leaf. (c) Cole Shoemaker, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • They appear as fuzzy bluish or white masses about 1/10 inch on shoot tips and leaves.[1]
  • Sticky honeydew is often the first sign.[1]
  • Winged adults have black-bordered wing veins and banded antennae.[1]

Look-alikes

Look-alikeHow to tell them apart
Citricola scaleThe only other insect that makes annoying honeydew on hackberry in California; brown to gray oval scales on twigs.[1]

Where it lives

Introduced from Asia, it infests Chinese hackberry and other Celtis, and occurs from Florida to Texas and north to at least Illinois.[1]

US map: public records from 25 states since 1990 (GBIF).

Biology and life cycle

Females give birth to live young through the season; eggs laid in fall overwinter on branch tips.[1]

In the San Joaquin Valley numbers peak in spring and fall, with many generations a year.[1]

Damage and signs

  • Copious honeydew grows black sooty mold on leaves and surfaces below; no long-term harm to trees has been found.[1]

Health risk

It feeds on hackberry; UC IPM mentions no risk to people.[1]

Control

Prevention

Treat only when honeydew becomes intolerable, since tree health isn't threatened.[1]

Biological control

Lady beetles, syrphid flies and lacewing larvae eat it, though often not enough; avoid broad sprays that disrupt citricola scale parasites.[1]

Common questions

Why is everything under my hackberry sticky?
Woolly hackberry aphid honeydew drips onto surfaces and grows sooty mold.[1]
Will the aphids kill the tree?
No. Years of infestation haven't caused serious damage.[1]

Sources

  1. University of California Statewide IPM Program, “Pest Notes: Woolly Hackberry Aphid (Publication 74111).” ipm.ucanr.edu/PMG/PESTNOTES/pn74111.html (accessed 2026-10-06)
  2. iNaturalist, “Shivaphis celti taxon page (order and family).” www.inaturalist.org/taxa/335282 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.