By Mike Kilpatrick, Southwest Division Technical Specialist, Terminix International
Photographs courtesy of Terminix
Aphids are insects all gardeners should be aware of. Although most infestations are light, heavy infestations can cause leaf curling and stunting of growth on new shoots of foliage, killing mature plants.
Wooly apple aphid
These insects have protruding mouthparts that enable them to pierce the tender portions of plants to suck out the fluids. Aphids come in a variety of colors including green, yellow, brown, and red, with others having a waxy or wooly appearance.
Most species have tube-like structures projecting out of the tail end of their bodies. These cornicles exude a by-product called honeydew as a result of their feeding. The honeydew is a sticky substance that can in turn cause growth of sooty mold fungus on the plant leaves. Some species of aphids can inject a toxin resulting in leaf damage, including stunting the growth of the plant.
Sooty mold growth on leaves as a result of honeydew deposits
Some ornamental plants and vegetable plants can contract viruses as a result of aphids feeding, while some species of aphids inhabit the soil and damage roots of the plant.
Aphids rarely will kill mature plants, however the honeydew and sooty mold that develop can warrant treatment. Large populations can develop in the spring on new, tender foliage. And warmer temperatures can cause the populations to swell in great numbers resulting in more damage to the plant.
Inspecting plants on a regular basis to identify early spring presence of aphids is the first step for achieving control. The presence of ants on plants can also be a sign of aphids. Ants will tend the aphids to consume the honeydew as a food source. They will also ward off predators and protect the aphids from natural predators.
Leaf curl result from aphid feeding
Cultural controls such as pruning the infested leaves and new shoot growth can reduce aphid populations when they are light. Use of lady beetles is also an alternative by releasing these predators into the garden to feed on these plant-damaging insects. Readily available insecticidal soaps can also be used when populations of aphids begin to increase. Always read and follow the label directions of any material with insecticidal properties prior to use.
Our gardens are investments that need to be protected from the creatures that can do them harm. Always start early in the growth period of the plant by monitoring for the beginning signs of insect activity. Continuing to inspect and monitor our plants throughout the growing season will help protect them, which in turn provides the beauty and joy our landscapes give back to us.