We are surrounded and vastly outnumbered by insects! Knowing which ones are considered pests and which are not is an important part of gardening. Obviously, not all insects are pests, and not all pests are insects. So, let's talk about a few of the most common pests in the garden, how to recognize them, the damage they do, and how to control them.
The most damaging insects in the garden can sometimes be the hardest to see. Spider Mites are almost microscopic, but their signature damage is easier to spot. Dust-like "freckles" on the leaf surface are a sure sign of spider mites. Mites live on the underside of leaves and use piercing, sucking mouthparts to feed on chlorophyll, leaving foliage greyish and weak. Fine webbing at branch tips is even easier to see but indicates that the mites have used up the food source and are dispersing to find new sources. Control spider mites with insecticidal soap or horticultural oil, making at least three applications, one week apart.
Scale insects can be just as hard to see on plants, hiding in plain sight masquerading as part of the plant. Scale spends its adult life stationary on twigs, covers itself with a hard shell, and pretends to be part of the plant. Scale insects secrete waste material as a sticky spray of honeydew. Watch for this shiny, sticky material on leaves to let you know you have scale. Control scale with horticultural oil, applied three or more times, two weeks apart. Be consistent and control is not difficult.
Another by-product of several different insects is sooty mold. A thin black film that wipes off easily, sooty mold is not harmful to the plant at all but is an indicator of other insect problems. Look more closely to find the insect problem and treat accordingly. Once the infestation is controlled, the sooty mold will stop growing and eventually wash off, wear off, or be hidden by new growth.
Aphids are easy to spot and easy to control. They can be green, yellow, orange, brown, or even black. Aphids cluster on new growth at the tips of branches and are often accompanied by ants that will cultivate and protect the aphids from other insect predators. The ants are rewarded with food in the form of a drop of sweet honeydew. Removing aphids with a jet of water is enough to control them. Insecticidal soap or horticultural oil are also effective controls. Apply each time you see a herd of the plump, soft, slow-moving insects.
I'll mention one other insect pest that has just recently arrived in the Charlotte area. This insect targets our beautiful Crape Myrtle trees and as of now, there is no reliable permanent treatment. Crape Myrtle Bark Scale is a very visible fuzzy white insect that clusters on the stems of Crape Myrtle and create large black patches on the trunks and bark. Infestations can be slowed with systemics or horticultural oil, but there is currently nothing that will control, much less eradicate this insect. Watch carefully for this "new" pest, and hope a control is developed quickly.