The species Bemisia argentifolii and B. tabaci are two species of whitefly common to Canada. These insects are tiny, sap sucking flies which excrete sticky honeydew and cause yellowing or death of leaves. The honeydew excreted can also result in the formation of sooty mould. This disease can be detrimental to the overall health and photo-synthetic capabilities of the host plant. The two species aforementioned have a very broad host range such as cucurbits, tomatoes, peppers, cole crops, Hibiscus, poinsettias, and are also a major pest of greenhouses, greatly emphasizing the importance of the control of this pest early in the cropping season.
Fourth-instar nymphs have no waxy filaments or marginal fringes. Adults have white wings and yellow body. They hold their wings slightly tilted to surface or substrate and have complete-oval shaped compound eyes. This moth-like insect can reach at maturity 2 mm in length. They can always be found on the undersides of the plant host leafs, for which insecticide applications should be aimed to these surfaces to ensure contact and efficiency of the treatment.
When scouting for Whiteflies within a greenhouse, when one fly is observed, it is often said that there are at least 100 bugs hidden with in the plants. However, a more accurate infestation estimation is to sample an area of approximately one square inch per plant, and if more than 10 of 2-3 instar nymphs, or more than 3 adult whiteflies are found, an application should be performed soon after to prevent further damage to the crop.