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Whiteflies - Which species do you have?

Tiny whiteflies are not really flies, but are related to aphids. They use stylet like mouthparts to suck sugar-rich fluid from leaf veins, and then excrete the excess sugar as do aphids. These sugar wastes make the leaves and fruit sticky and allow a black mold to grow. Some species transmit a plant disorder that causes uneven ripening of the fruit. Two major pest species are common in both vegetable and ornamental greenhouses, the greenhouse whitefly and silverleaf whitefly.  Both have very braod host ranges.  The adults are almost impossible to distinguish when caught on yellow sticky cards.  This is a problem.  The common strain of Encarsia formosa parasitoids that has been used for decades to control the greenhouse whitefly are not effective against the silverleaf whitefly, also known as the Bemesia type.  The Control Page details strategies on whitefly control.

A third species of whitefly is commonly found in the mid-Atlantic states, but does not cause economic problems and can be easily distinguished with a hand lens. The dark transverse bands on it's white wings give it the common name of banded-winged whitefly.

For further information go to the USDA whitefly identification site.

Whiteflies on sticky cards. The white wax tends to dissolve in the sticky card coating making the wings transparent. Note the four wings. True flys only have two wings.	The wings of this Bemesia type whitefly are held at more of an angle compared with the greenhouse whitefly, but it's hard to tell on a sticky card. The nile strain of Encarsia formosa works well on both "Bemesia" and "Greenhouse" whiteflies .
	Banded whitefly adult captured on a sticky card. These whiteflies are common in mid-Atlantic regions and are often found in greenhhouses, but have not been reported in outbreak numbers and are not known as a problem.