Whitefly                           Family: Aleyrodidae

Host plant(s): multiple species

Adult size: varies by species, but generally – 
                        body length: 0.04-0.08 inch (1-2 mm)
                        wingspan: > 0.12 inch (3 mm)

Type: Pest

Life cycle: 
            Generations per year: multiple
            Egg: one week
            Nymph: 4 instar stages
            Pupa: unknown duration
            Adult: about 30 days

 

Description & Life Cycle: Whiteflies are not true flies. They are more closely related to aphids, mealybugs and scale. This puts them in the order of Hemiptera rather than in the order Diptera with the true flies. The name “whitefly” comes from the white wax covering on the wings and body of the adults.

Females lay 200 to 400 eggs in groups of 30 to 40. Eggs hatch in about a week into flattened nymphs with tiny legs. These crawlers, as they are called, will wander around the plant before settling in one spot and inserting their mouth part into the plant to start feeding on its sap. This crawler stays in one place through the next three instar stages…growing larger and losing its tiny legs as it grows larger. At the end of the 4th instar stage, the nymph enters the pupa stage, although technically it does not go through a true complete metamorphosis. Adults emerge to mate and live about a month.

Some adult whitefly species have distinctive markings on their wings but many have no markings. In the nymph stage, colour can be black with a white fringe, transparent yellow or white depending on species.

Whiteflies typically overwinter on plant debris and in branch crevices…although I could not find any mention in which life cycle stage this occurs.

  

Special Notes: There are over 1500 species of whitefly, most of which will feed on only one or a few species of plants. All whitefly species are sap-sucking feeders and a few are responsible for transporting viruses from plant to plant. They are difficult to identify in their specific species designation but are easily recognizable by the cloud of white which will erupt when an infested plant is disturbed. Another indication of a whitefly problem is sticky patches on the upper side of leaves caused by the honeydew excretions from whiteflies feeding in the undersides of leaves higher up on the plant. Another clue can be black sooty mold on the upper side of leaves which develops on the honeydew. While this looks unsightly, it rarely does any serious harm to the plant.

 

Remedial Actions: Whiteflies have many natural enemies in the garden including ladybugs, lacewings, spiders and predator bees as long as you do not use chemical sprays. These sprays are also harmful to beneficial insects.

Another solution is to use yellow sticky traps…although these will catch beneficial insects as well as the pests.

Best remedy of all is to provide appropriate water and nutrients to your plants to guard against pest infestation. Healthy plants are much, much better at thwarting pests from attacking them than those plants which are struggling because they are underfed or underwatered.

 

Posted on February 26, 2020