Pest profile

Cabbage Whitefly

Aleyrodes proletella · Hemiptera: Aleyrodidae[2]

The cabbage whitefly is a newer pest of cabbage, kale and other brassicas, including ornamental kale, that curls and yellows outer leaves and coats them with honeydew.[1]

Cabbage whitefly adult, tiny and white with white wings, on a green leaf
Cabbage whitefly adult, tiny and white with white wings, on a green leaf. (c) Frank Ashwood, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Adults are under 0.05 inch long, white and mothlike, with white wings and a waxy white thorax; when abundant they fly up in clouds.[1]
  • Nymphs are whitish green, flat and oval, and covered with dense wax.[1]

Look-alikes

Look-alikeHow to tell them apart
Greenhouse whiteflyHas longer wings, a yellow thorax and a much wider host range.[1]

Where it lives

The PNW Insect Management Handbook covers it as an emerging pest of brassica crops and ornamental brassicas in the Pacific Northwest.[1]

US map: public records from 13 states since 1990 (GBIF).

Biology and life cycle

Adults overwinter on host plants, including nearby related weeds, and can spend the whole year on one plant.[1]

When problems persist, check nearby brassica weeds; as they mature or die off, whiteflies move to more valuable plants.[1]

Damage and signs

  • Damage is usually limited to curled, yellowed outer leaves and sooty mold on honeydew, especially on ornamental kale.[1]
  • Adults and nymphs can spread a great number of plant viruses.[1]

Health risk

It feeds on plants; the PNW Insect Management Handbook mentions no risk to people.[1]

Control

Prevention

Monitor with yellow sticky traps next to suspect plants, and look closer when paper wasps and yellowjackets patrol the beds.[1]

Keep them out

Isolate new plants until you've checked them for eggs, nymphs and pupae, since adults may not be present on arrival.[1]

Biological control

The parasitic wasp Encarsia formosa and predatory Delphastus beetles are effective biological controls.[1]

Common questions

What are the tiny white flies swarming my kale?
Likely cabbage whiteflies; when abundant they fly up in clouds from brassica plants.[1]
How is cabbage whitefly different from greenhouse whitefly?
Greenhouse whitefly has longer wings, a yellow thorax and a much wider host range.[1]

Sources

  1. Pacific Northwest Pest Management Handbooks (OSU, WSU, University of Idaho), “Emerging Insect Pests in the Pacific Northwest: Cabbage whitefly (2016).” pnwhandbooks.org/insect/emerging-insect-pests/emerging-insect/cabbage-whitefly-2016 (accessed 2026-10-06)
  2. iNaturalist, “Aleyrodes proletella taxon page (order and family).” www.inaturalist.org/taxa/409563 (accessed 2026-10-06)

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