Greenhouse Whitefly

Latest Update 18th August 2016.

Greenhouse Whitefly. 
  • After living in greenhouses and feeding off the sappy green foliage of greenhouse vegetables for decades, greenhouse whitefly have built up resistance to chemical pesticides, and have carried that resistance with them to the backyard garden.
  • I have always had a few whitefly in my garden, but in recent years they have become a serious pest.  They are difficult to control, especially if allowed to become established in spring, and I believe the only way to control them in a suburban environment without spending lots of time or using expensive organic pesticides is to use natural predators.  To do this you need to create a natural environment with lots of insect attracting plants in your garden. 
Details.
  • Binomial name                                            Trialeurodes Vaporariorum.
  • Family:                                                       Aleyrodidae
Why Greenhouse Whitefly are a Pest.
  • In small numbers they don't have much effect on plants, but they multiply quickly and in large numbers can cause a lot of damage.  They exude honeydew, attract ants and the adults can transmit viral and fungal pests which can kill plants very quickly.
Pest Control.
  • Grow lots of flowering plants especially herbs to attract natural predators like hoverflies, lacewing, ladybirds and praying mantis.  This is the best way to control chewing insect pests, but while your predators are getting established you may need to use other measures.
  • A monthly foliar spray of aerated compost tea provides plant foliage with some protection against insect and microbial pests, but to control a substantial whitefly attack, I use organic horticultural oil, which smothers them in the nymph and adult stages of their life cycle.  I follow up in a day or two to ensure whitefly hatchlings are killed as they emerge from their protective pupae stage.
  • Take care to target only the whitefly and avoid collateral damage amongst beneficial insects.  Start looking for signs of whitefly in late winter and attack them early so they will be easier to control later in the season.