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Greenhouse Whitefly

The greenhouse whitefly is one of the most common houseplant pests.

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NAME: Greenhouse Whitefly (Trialeurodes vaporariorum)

BIOLOGY: Brush against an affected plant and you will be greeted by a cloud of small, white, moth-like insects. With the same piercing mouthparts as aphids, whiteflies consume plant sap, and in turn deposit sugary honeydew on the surface of leaves where they are feeding. The adults, less than one-eighth-inch long, live for up to two months, during which time they may lay 200 eggs. These hatch within a week to become translucent nymphs called crawlers, which wander for a short distance before permanently settling down to feed.

After their first molting, these nymphs lose their legs and antennae and look like tiny scale insects covered with a white waxy secretion. After an additional week or so of feeding and molting, the nymphs pupate, emerging a week later as adults.

The females, without having to mate, then begin laying eggs, completing the life cycle in a mere four to six weeks. Indoors, where conditions are uniformly warm, matching the whitefly's tropical origin, populations can grow extremely rapidly.

SYMPTOMS: Whitefly feeding results in yellowed or mottled leaves and reduced plant vigor. Leaves may shrivel up and drop prematurely. Excreted honeydew collects dust and supports the growth of black, sooty mold fungi. Adults flying above foliage indicate a likely infestation.

CONTROL: Prevention is the best strategy. Inspect new plants carefully prior to bringing them into your home or greenhouse, and quarantine them for at least a month while monitoring them for signs of whitefly.

Flying adults, which are attracted to bright yellow surfaces, can be trapped with commercially available yellow sticky traps. Or, you can create your own traps with Rust-Oleum 659 or Safety Yellow paint, coating the panel or card with mineral oil or other insect-trapping material such as Tack Trap.

Small, handheld vacuums can also be used to suck up the adults. Placing the vacuum in a freezer for 24 hours will kill the contents.

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