A few years ago, I noticed whiteflies on two confederate rose plants in my landscape. I considered using an insecticide to control the whiteflies but decided against doing so after taking a closer look at the leaves. What I found was a tremendous population of ladybeetles – adults, larvae and pupae.
Ladybeetle adults and larvae eat whiteflies. They also eat other soft-bodied insects such as aphids. So, I waited to see what would happen.
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At first I was seeing mostly adult whiteflies, which look like tiny white moths. Adult whiteflies mate and then lay eggs on the underside of leaves. The eggs hatch into flat translucent scale-like nymphs that suck the sap from the underside of the leaves.
Eventually, some of the leaves developed a black coating called sooty mold. As certain insects (primarily aphids, some scales and whiteflies) feed, they excrete plant sap that coats the leaves. Sooty mold then grows on this sugary sap. It’s not a pathogen. It just makes the leaves look ugly.
Knowing that the whiteflies would not kill the confederate rose plants, I was willing to tolerate the sooty mold and allow the lady beetle population to build.
Allowing whiteflies to live on your plants may not always be the best option. But in order to have beneficial insects in your landscape, there must be some “bad” insects.
Insects such as ladybeetles, lacewings and praying mantids eat many pest insects. Encouraging these beneficial insects can allow you to reduce the amount of pesticides that you need to apply.
It’s important to learn to recognize the adult and immature stages of these beneficial insects. For example, ladybeetles have larvae that look nothing like the adults. Some ladybeetle larvae look like small orange and black alligators. Others may resemble mealy bugs. Many gardeners that would never kill adult ladybeetles mistake ladybeetle larvae as pests and kill them with pesticides.
The following UF/IFAS Extension website will help you learn to recognize many of our beneficial insects. https://edis.ifas.ufl.edu/topic_beneficial_insects
Once you find beneficial insects in your landscape, reduce or eliminate the use of pesticides. When a pesticide is needed, use environmentally friendly options such as insecticidal soaps, horticultural oils and products that contain Bacillus thuringiensis. These products can help maintain the population of beneficial insects.
Sometimes a heavy stream of water from a water hose is all that is needed to remove pest insects from plants and reduce their numbers to an acceptable population.
Leaving a few pest insects is a great way to attract beneficial insects. Tolerating a minor infestation and a little plant damage will benefit the helpful insects, your pocketbook and the environment.
Larry Williams is the Extension horticulture agent with the Okaloosa County Cooperative Extension Service, University of Florida. Contact Larry at 689-5850 or email [email protected].
