Home Gardening

Insects bugging Coast plants
The Coast Gardener Newspaper and Web Column - July 13, 2002

Two insects can be extremely pesky this time of the year. I have noticed both white flies and aphids enjoying the juices of several ornamental shrubs lately. The increased rainfall has made the mosquitoes happy, too! I'll leave that sore subject for another day.

White flies are very small moth-like insects that are covered with a white, waxy powder. Since they are only about 1/8 of an inch long, they can be hard to spot. The immature insects actually cause the damage. At this stage, white flies can resemble miniature scale insects. These pests are found on the underside of foliage.

They suck sap from the leaves and secrete that sticky substance called honeydew as they chow down on your favorite plants in your landscape. The honeydew causes a black fungus called black sooty mold to grow. This causes the plants to appear as if they have been dusted with black soot.

Many gardeners blame the sooty mold for their plants' demise, but the mold really doesn't affect your plants unless it gets so bad that sunlight has trouble reaching the leaves.

Gardenias are favorites of white flies. A friend of mine recently had such an infestation that you could shake the branches and a cloud of white flies would swarm around. An insecticidal soap worked liked a charm; after a few days they were gone. Other insecticides are available for white fly control, but read and follow label directions carefully to avoid plant injury. Adequate control is achieved when the spray is directed toward the underside of the leaves.

Aphids are tiny, soft-bodied insects that are sometimes called plant lice. Aphids reach 1/4 inch in length and can be black, yellow, green or red in color. They suck the juices from the tender parts of plants. Aphids, like white flies, produce honeydew.

Since aphids have soft bodies, insecticidal soaps work well. Even a strong stream of water from the garden hose will sometimes work, especially if infestations are not too severe. If the above solutions do not seem to work for you, there are many available insecticides that list aphids on the label. Always make sure it is okay to use a product on your affected plants by reading the label carefully.

Finally, gardeners want to know how to get rid of the black sooty mold. Once the insects are controlled, the mold will eventually disappear. However, gardeners do not have to wait that long.

Try spraying the foliage with a soap and water solution. Mix a couple of teaspoons of liquid dishwashing detergent in a gallon of water. Let the soap solution remain on the plant about 15 minutes and hose it off. A strong stream of water from the garden hose will removed the loosened sooty mold.

Many popular broadleaf evergreen shrubs and even garden vegetables are susceptible to white flies and aphids. With correct identification and control measures, these bugs won't "bug" your garden very long.

These archived gardening columns were written by Chance McDavid, former Harrison County Extension Agent.