Ways to control aphids include biological, cultural and chemical methods. Monitoring plants during the growing season also gives the gardener a chance to control the pests by trimming parts they infest or washing them away with a hose before the problem becomes severe.
Biological control of aphids involves releasing ladybugs to eat the pests and managing ants, which sometimes farm aphids to produce honeydew as a food source. The gardener should release ladybugs at dusk to prevent them from flying away. They offer temporary control at best, as most eventually leave the tree where the gardener places them.
Clearing the area of any aphid infestations before planting is one method of cultural control. Reflective mulch, including silver plastic or silver spray painted materials, placed around the base of plants seems to be effective at keeping aphids from attacking.
While most large trees survive aphid infestations, and the number of aphids decreases as temperatures rise, in some cases chemical control becomes necessary. Most of the time, gardeners are able to achieve control using insecticidal soaps or horticultural oils. These chemicals do not leave residue, so they do not disturb the natural aphid predator population. Contact-only sprays are generally ineffective for gall-protected aphids. Some of these sprays cause damage to the plants by reacting with sunlight.