Aphids on Trees
Aphids on Trees and Shrubs
Many species of aphids occur on ornamental trees and shrubs in the Atlanta area. Certain species feed on foliage, others on twigs and branches, flowers or fruit, and some on roots. Aphids live on several distinct hosts, spending part of their seasonal development on one host and the remainder on another. They feed on both coniferous and deciduous plants. Effective control of aphids has been a problem to homeowners for years. Some of the more common aphids include the green peach aphid, melon aphid, tulip tree aphid, giant bark aphid, white pine aphid, and rose aphid.
Aphids constitute a large group of small, soft-bodied insects. They may measure up to 6 mm in total length. Aphids have piercing-sucking mouth parts that enable them to remove plant fluids from a host. Aphids generally can be recognized by their pear-like shape, a pair of cornicles (tube-like processes) at the posterior end of their body. The cornicles secrete a defensive fluid which warns aphids of predators and other enemies. Aphids vary in color from green, yellow, red, purple, brown, or black.
In some cases, cultural practices such as proper pruning, fertilizing, and watering play an important role in preventing or suppressing an aphid infestation. When practical, try washing aphids off an affected host with a strong stream of water. Many trees, shrubs and flowers have resistance to aphids. Observe those plants in the neighborhood to identify those that seem to be annual "aphid food" and those that never seem to be bothered. Select the resistant types for your own yard.
Beneficial insects play an important role in aphid control. Ladybird beetles (both adults and larvae), lacewings, some flower flies (larvae), and tiny parasitic wasps will use aphids as a source of nourishment for their development. Remember certain insecticide applications will destroy these beneficial insects as well as targeted pest species. This practice could leave trees and shrubs unprotected if pest populations should increase in the future.
The use of insecticides is often the only effective means of controlling an aphid infestation. We use a number of registered formulations of insecticides that are available for aphid control.
Aphids have sucking mouthparts and are thus very susceptible to pesticides located in the plant vascular system. Some of the systemic insecticides also have contact activity.
Is the most effective way to control aphid populations.
Since most aphids are soft-bodied insects, horticultural oils and insecticidal soaps seem to provide good control.