White Flies

White FlyWhite Fly Adult

White FliesWhite Fly Adults
(Whitney Cranshaw, Colorado State University, Bugwood.org)

White Fly NymphsWhite Fly Nymphs
(John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org)

HOSTS

  • Greenhouse/High Tunnel Crops
  • Brassicas
  • Legumes
  • Corn
  • Solanaceae Crops
  • Leafy Greens
  • Cucurbits
  • Potato
  • Root Crops
  • Hemp

DESCRIPTION

Adults are tiny with bright white wings and yellow-orange heads. Immature stages are inconspicuous with pale, almost translucent, flat bodies that are mostly immobile. 

BIOLOGY

Whitefly populations continue from year to year in greenhouses and in the far south. There are several generations per year. During warm weather, on transplants, or when natural enemies are disrupted by insecticide applications, dusty conditions, or interference with ants that are attracted to the honeydew secreted by whiteflies.

Egg | Nymph | Pupa | Adult
  • Several generations per year.
  • Populations continue from year to
    year in greenhouses and in warm
    southern climates.

DAMAGE SYMPTOMS

Adults and nymphs feed with piercing-sucking mouthparts, causing leaves to turn yellow, appear dry, or fall off plants. Whiteflies, like aphids, also excrete a sugary substance called honeydew, causing shiny, sticky leaves or sooty mold growth on leaves.

GENERAL MANAGEMENT

  •  Attract and conserve natural enemies
    as they often provide adequate
    control.
  • Inspect transplants and remove any
    with high whitefly populations.
  • In greenhouses, use biocontrol (such
    as hanging cards with Encarsia sp.).
  • Approved insecticides are available.
Time for Concern: During warm
weather and on transplants.

When and Where to Scout: In the greenhouse, monitor with yellow sticky cards to detect whitefly presence. Look for large colonies during warm weather on the underside of lower leaves. Honeydew may also be noticeable on the tops of leaves. Before planting, inspect transplants for whiteflies.

Threat Level: High for greenhousegrown hemp.

Occurrence in Utah: Whiteflies have not yet been found feeding on field-grown hemp in Utah, but whitefly damage has been found in neighboring states.  Economic damage from whiteflies in the garden or field is rare in Utah and is more commonly seen in greenhouses or high tunnels.

INSECTICIDES

Whiteflies develop resistance to insecticides quickly and treatment is not generally needed for garden plants in Utah. Greenhouse plants have a threshold of 10 nymphs/leaf.

Precautionary Statement: Utah State University and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks, and not all are registered for edible crops. “Restricted use” pesticides may only be applied by a licensed applicator. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed in this publication.