How to Identify and Manage Whiteflies
Whiteflies are not a very common pest in the interior landscape, but with some of the new invasive whitefly species we now have in the US they could soon become an issue for interior plants.
They are easy to recognize because they look like their name. These little insects do their damage by sucking the sap from plants, producing honeydew, leaving waxy filaments and can be a visual nuisance.
Why Are Whiteflies So Destructive?
Whiteflies have piercing mouth parts that they insert into plants to feed on the sap. They excrete honeydew, and when whiteflies are in abundance, this can become an issue.
How to Identify Whiteflies
Adult whiteflies are soft-bodied insects that have white wings with a yellowish body. When disturbed, they will often fly off the plant. The adult females lay their eggs on the underside of leaves, sometimes in a circular pattern. Whitefly nymphs are oval, yellowish and can have white waxy filaments (not legs) around the body.
The Life Cycle of a Whitefly
In warm temperatures, whiteflies can develop quickly. Adult female whiteflies can lay between 200 and 400 eggs, in a circle or spiral pattern. The pattern will depend on specific species. About a week after being laid, the eggs hatch into crawlers that disperse on the plant. They will then insert their straw-like mouthparts and begin to extract plant juices. After feeding they will pupate and a new whitefly will emerge. How long it takes for the whiteflies to develop from eggs to adults varies with species, but on average it is 4 weeks.
Do You Have a Whitefly Infestation?
- White gnat looking insects flying around plants
- Dropping and yellowing leaves
- Stunted or distorted growth
- Whiteflies on yellow sticky cards
- Sometimes sooty mold can be found when high populations are present
It’s Time to Take Back Control
Before you treat make sure you really have whiteflies on your interior plants as they are not commonly found indoors. If you do get them, removal of infected plants would be the first option. There are some biological control agents for some of the whitefly species, but many of these beneficial insects fly and your clients probably do not want to have anything else flying around their interior landscape. A better option would be to treat with products like insecticidal soap or a horticultural oil. For soaps and oils to work, you must spray the underside of the leaves where the whiteflies are located.
Chemical insecticides like Safari (dinotefuran) and Flagship (thiamethoxam) can be used as a drench on the interior and can be very effective. Another option is Endeavor (pymetrozine). This is a foliar applied insecticide that paralyzes the mouth parts of whitefly, preventing them from feeding.
Pest control labels vary between states and the pesticide user bears the responsibility of consulting the pesticide label and adhering to the law. Always read the label before a pesticide is applied to make sure it is legal to apply on your site, in your state and the plant material.
Preventing Whitefly Infestations
Always check plant before taking them for installation. As mentioned, whiteflies are not currently an interiorscape pest but you could get them on seasonal color like poinsettias. Poinsettias are an excellent host for whiteflies. If you do get them on poinsettias, it might be best to just replace the plants because treatment can be tricky once the plants are in color.
Yellow sticky cards are a way to trap for adult whiteflies. They are attracted to the yellow and get stuck on the card. This method can also be used to detect if they are in the area.
Battling other common indoor plant pests? Check out my Professional’s Field Guide to Plant Pest Control for information on Spider Mites, Thrips, Fungus Gnats, Mealybugs, Aphids, and Scale insects.
Featured image by Fluffymuppet via https://www.flickr.com/photos/fluffymuppet/4904738679/