Evergreen Arborist Consultants recently received a call from a homeowner regarding aphids that infested her birch trees. She was very concerned about treating the aphids without harming her pets. The aphids were damaging the birch tree leaves and staining her concrete from the honeydew. Honeydew is a sticky black liquid, secreted by aphids as they feed on plant sap. Ants were also attracted to the sugar-rich substance and were as much of a nuisance as the aphids. Aphids are among the most destructive insect pests on ornamental plants. Aphids are small, soft-bodied insects with long slender mouthparts that they use to pierce stems, leaves, and other tender plant parts and suck out fluids. The damage they cause to plants has made them enemies of farmers and gardeners. Large populations can turn leaves yellow and stunt shoots. Aphids may transmit viruses from plant to plant on certain vegetable and ornamental plants.
When considering whether to apply insecticides for aphid control, remember that many larger plants can tolerate light to moderate levels of aphid infestations. Larger aphid populations typically decline due to hot weather. One method of controlling aphids is spraying a high volume of water to the underside and tops of leaves. If that’s not effective, apply water-soap solution insecticidal soap. The insecticidal soap uses potassium salts of fatty acids. The potassium salts weaken the insect’s waxy protective outer shell. Be sure to follow the label’s directions. Insecticidal soap is highly preferable to chemical pesticides because it possess toxins that can kill beneficial insects which don’t cause long-term detrimental effects on the environment. Repeated application may be necessary as these pesky bugs tend to return if left untreated.