• Whiteflies are tiny, white, winged insects that have been noted in many soybean fields.
• These insects are seldom a significant threat and insecticide application is unlikely to be necessary.
• In addition to the whiteflies that you may be currently seeing in soybean fields, there is another commonly encountered species that feeds on velvetleaf (banded-wing whitefly).
• Yellowing and wilting of soybean leaves may occur when nymphs and adults both feed on leaves.

However, in the soybean fields we have scouted this year, where whitefly activity is present, only adults have been observed.

Whiteflies are tiny, white, winged insects that have been noted in many soybean fields.In some cases, numbers have built up to levels where these insects “fog off “ the soybeans during scouting visits.Whiteflies and their immature stages (nymphs) feed with piercing and sucking mouthparts, mostly on the underside of soybean leaves.In most fields, in spite of the “fogs” of adult whiteflies observed in fields, these insects are seldom a significant threat and insecticide application is unlikely to be necessary.

Female whiteflies live for 10 to 24 days and lay between 66 and 300 eggs, depending on the plant host and environment.The flies often turn as they lay the eggs, so the eggs are laid in an arc on the underside of the leaf. (Image 1 below) Eggs hatch in about a week at room temperature.

Image 1:  Whitefly egg mass

There are 4 nymphal or larval development stages.(Image 2 below)Nymphs are very small, oval in shape, and flattened.They are pale, almost transparent, in appearance.The first stage nymph is a crawler that can move a short distance from its hatch site.The 2^nd, 3^rd, and 4^th instar nymphs settle at one feeding site and don’t move any farther.

Image 2:  Whitefly larvae or nymph

Development of whitefly nymphs takes a total of about 11 to 15 days, so a whole generation is complete in 3 to 4 weeks.

There are several species of whiteflies.Some are very host specific, while others have a broad host range.In addition to the whiteflies that you may be currently seeing in soybean fields, there is another commonly encountered species that feeds on velvetleaf (Image 3 below - banded-wing whitefly).Where whiteflies become a problem, yellowing and wilting of soybean leaves may occur when nymphs and adults both feed on leaves. (Image 4 below – greenhouse whitefly adult) It generally takes a very large number of whiteflies and their nymphs to cause wilting of soybeans.

Image 3:  Banded wing whitefly

Image 4: Greenhouse whitefly adults

In the past, Kentucky has reported presence of the silverleaf whitefly, also called the sweetpotato whitefly.This species is particularly troubling because it transmits viruses of cucurbits and tomatoes, and is resistant to several insecticides.Though they look much alike, there are features of both the adult and nymphs that can be used to identify them.In particular, the sides of the greenhouse whitefly are perpendicular to the leaf surface (Image 5 below), whereas the sides of the silverleaf whitefly are sloped or angled.

Image 5:  Perpendicular sides of the greenhouse whitefly larvae