Whiteflies

whitefliesBiological information:

  • Common name: White Flies
  • Family or class: Aleyrodidae
  • 3 types
    • Greenhouse White Flies
    • Banded-wing White Flies
    • Silverleaf White Flies
  • Not actually a Fly, but more related to aphids, scales, and mealybugs

Symptoms and or signs to watch out for:

  • Adult bodies and wings are covered by a mealy white wax that gives them their name
  • Large colonies can form on undersides of leaves
  • Growth of sooty mold
  • Stem blanching
  • Chlorotic spot
  • Leaf yellowing and shedding

Life cycle:

  • 6 stages: Adult, egg, three nymphal instars, instar or pupa
  • All occur on underside of leaves
  • Most reliable ID is in pupal stage
  • One whitefly can go from egg to an adult in 16 days
  • Only live for a month or two

Mode of reproduction:

  • Eggs are laid on underside of leaves and one female can lay hundreds of eggs, typically in a circular pattern
  • In warm climates and in greenhouses, reproduction is almost continuous

Horticultural production information:

Preventative strategies:

  • Limit pesticide use to keep natural predator population high
  • Limit dusty conditions
  • Hosing down plants
  • Interference by ants can cause outbreaks

Threshold levels:

  • varies depending on if it is hosting pests, if it is directly in bed/on side, etc.

Control options:

Physical controls:

  • Water- Jet of water can knock whiteflies off of plants and leaves
  • Yellow sticky tapes
  • Aluminum Reflective Mulch- The mulch makes it difficult for whiteflies to find host plants
  • Vacuum

Biological controls:

Predators include-

  • Lacewings
  • Bigeyed bugs
  • Minute pirate bugs.
  • Small lady beetles- on Ash whitefly
  • Scymus  

Parasitic insects-

  • Encarsia spp. –parasitic insects, recommended only for greenhouse and perform poorly outdoors
  • parasitiod wasps (encarsia fomosa)
    • thrive best in temp 65-85 F
    • economical and used for wide range of crops
  • parasitiod wasp (eretmocerus cremicos)
    • more effective in controlling silver leaf white fly
    • WF larvae must be present
    • above 70 introduce 6 per m2
    • can tolerate high temps

Chemical controls:

  • Insecticidal soaps
  • Neem oil
  • Petroleum- based oils
  • Whiteflies can be difficult to control with insecticides because they occur mostly they are mainly on the underside of leaves and typically the lowest leaves

Historical notes from Farm to YoU NH:

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