7/2/2013 - By Matthew Shultz

This month let’s focus on an insect that is sure to show up in nurseries and greenhouses in the next couple of months, the whitefly!

Whiteflies can take on many different looks and appearances as they grow from egg to adult. Eggs are laid by females on the underside of the leaves. Within two weeks, the eggs hatch and a nymph emerges that has six legs, but at this point it doesn’t have any wings. Actually at this stage the whitefly nymphs look more like a scale insect. These lightly colored nymphs are flat and circular to oval in shape. Still located on the underside of the leaves, the whitefly nymph usually crawls around for a few hours before it settles down and starts to feed, and will remain in this place until it pupates.

Whiteflies pierce the leaf tissue and insert a feeding stylet, then suck out the liquid, depriving plants of nutritional value. A whitefly remains a nymph for a couple days to a couple of weeks depending on environmental conditions. After that it will pupate and become an adult. The adults now have two sets of wings. Most species are white in color but some species can be pink to tan in color, and can grow up to 1/16” in length.

In order to scout for these pests, growers obviously need to look at the leaf undersides of their crops. Larger populations of whiteflies can actually cause yellow stippling on the upper side of the leaves too, and can be confused with spider mite or lacebug feeding. Whiteflies also excrete honeydew when they feed, and this honeydew serves as a breeding ground for sooty mold. Growers should look for black mold growing on the leaf surfaces.

There are many chemical options available for whiteflies, but there are also many naturally occurring predators and parasitoids of this pest, so compatible sprays can pay large dividends. Compatible products include Flagship, Safari, TriStar, Imidacloprid, Botainguard, Avid, Endeavor, Conserve, Distance, Enstar II and hort oils. For quick knockdowns of high populations apply Acephate, Sevin, M-Pede or Talstar.