Insect of the Month - Greenhouse Whiteflies

  Hort Snacks - January 2019
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 Causal Organism: Trialeurodes vaporariorum (greenhouse whitefly – GFW)); Bemisia tabaci (sweetpotato whitefly); Bemisia argentifolia (silverleaf whitefly)
  • The specific species present may vary by region
Crops Affected: Wide host range (250+ species) – a range of greenhouse vegetable crops (e.g. tomatoes, cucumbers), as well as ornamentals (poinsettia, cut flowers, bedding plants, house plants, etc.)

Life Cycle:
  • True bugs – feed on plant sap by piercing and sucking
  • May cause a reduction in plant vigour and some secondary sooty moulds (due to sticky honeydew)
  • Life stages include eggs, nymphs (crawlers), pupae, adults
  • Life cycle is affected by temperatures, with shorter times at warmer temperatures
  • Sensitive to cold temperatures
  • Adults
    • Small (1.5-2mm), powdery white winged insects
      • GWF has the wings held flat and parallel to the resting surface, and the overall body shape is triangular
      • B have the wings in a tented fashion above the body, and the overall body shape is more linear
    • Difficult to see with the naked eye
    • Adults lay 100-300 eggs (over a 3-5 week lifetime) along the undersides of younger leaves
  • Eggs are sometimes laid in circular “fairy-ring” patterns
    • Eggs start off a creamy-white, darkening within a day or so
  • Nymphs
    • Eggs hatch in 5-10 days to produce a flat, scale-like, largely immobile nymphal stage, referred to as “crawlers”
    • Nymphs pass through 3 instars before pupation
  • Pupae
    • Pupation lasts about 1 week, with no feeding taking place
      • GWF pupae are somewhat raised off of the surfaces of the leaves, and may be surrounded by a fringe of hairs
      • B pupae sit flat on the leaf surface and have no hairy fringe
Multiple life stages of Greenhouse Whitefly
Trialeurodes vaporariorum)
Adult Silverleaf Whitefly (Bemisia argentifolia)
Photo by Whitney Cranshaw, Colorado State University,
Photo by Scott Bauer, USDA Agricultural Research Service,

  • A decline in plant vigour
  • Stunting, yellowing of leaves and premature leaf drop
  • The observation of the insects stages may be indicative of presence
  • Some species transmit plant viruses, which produce other symptoms
  • Monitor / inspect plants regularly for pests
    • Quarantine new plants to ensure they are not bringing in a problem
  • Use pest-attractive plants as trap or monitoring sites (e.g. eggplants)
  • Apply controls quickly to prevent populations from increasing rapidly
  • Control alternative hosts (e.g. weeds) in adjacent areas
  • Use clean, virus-free plants (to avoid virus transmission)
  • Biological controls can be effective at managing populations of whitefly, including specific parasitic wasps, ladybeetles, predatory bugs and a couple of different fungal biocontrol products.
  • Yellow sticky traps or yellow sticky tape can be used broadly and/or in population hotspots to draw whiteflies
    (and other insects) out of the crop
  • Vacuuming adults from hotspots can work to quickly bring a population in one area down, however this is not effective in larger areas
  • Install fine-meshed screens over vents and doorways, to prevent entry and movement between areas, and from outside to inside a greenhouse
  • Registered chemical controls may be applied at specific stages to reduce populations
    • Use these with care to prevent the development of resistance
    • Certain products are more effective on certain life stages (e.g. horticultural oils are best for immobile, immature stages
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For more information about the content of this document, contact Robert Spencer.
This information published to the web on December 12, 2018.