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How to Kill Whiteflies on Gardenias

By Meg Butler ; Updated September 21, 2017
Don't let whiteflies take over your gardenias.

Whiteflies are hard to miss. Every time you water or walk by your gardenias, they fly up in pesky white swarms. Or, you may have noticed their eggs on the underside of your gardenia’s leaves. Whatever the sign, it’s important to kill white flies as soon as you notice them. These insects spread rapidly, especially in the warm southern areas, and can quickly overwhelm a gardenia bush. Large enough numbers of them will strip its foliage, potentially spread viruses and diseases, and maybe even kill a weakened plant.

Destroy any whitefly eggs that you may find growing on the underside of your gardenia's leaves. Prune the leaves and dispose of them. Crush the eggs or spray them with horticultural oil.

Suck large swarms of whiteflies up with the hose on your vacuum.

Spray the adult population. Whiteflies are quite susceptible to a number of controls: insecticidal soap, neem and horticultural oils, and pesticides like purethrum, permethrin and bifenthrin. The trouble lies in the application. All of these methods work by contact, and whiteflies are quick little blighters. Whichever method you choose, you will likely need to spray your gardenias once weekly for a month. And when you do spray, aim at the underside of your gardenia's leaves where the whiteflies live.

Release beneficial insects into your garden. Ladybugs (Delphastus pusillus), green lacewings (Chrysoperla spp.) and predatory mites (Euseius spp.) all feed on whiteflies. If you release beneficial insects, abstain from spraying your gardenias. The pesticides will kill the beneficial insects as well.

 

Things You Will Need

  • Vacuum
  • Pruning shears
  • Insecticidal soap, horticultural oil or pesticide
  • Beneficial insects

Tips

  • Your whiteflies may be a sign that your gardenias are suffering from phosphorous or magnesium deficiencies.
  • Large populations of whiteflies can be difficult to control. If a combination of control methods fails, you may need to uproot your gardenias and replace them with a whitefly-resistant plant.

About the Author

 

Based in Houston, Texas, Meg Butler is a professional farmer, house flipper and landscaper. When not busy learning about homes and appliances she's sharing that knowledge. Butler began blogging, editing and writing in 2000. Her work has appered in the "Houston Press" and several other publications. She has an A.A. in journalism and a B.A. in history from New York University.