The Ant-Aphid Connection
from: June 13, 2010 Techletter
Problems with Argentine ants, carpenter ants, ghost ants, white-footed ants, and many other species in and around buildings can often be traced to the ants feeding on “honeydew” in nearby trees, shrubs, or on foundation plantings. Roughly three quarters of the pest ants we deal with feed at times on honeydew.
Honeydew is a sugary substance that is exuded from the anal end of aphids and certain other plant sucking insects such as mealybugs, scale insects, white flies, and plant hoppers. The ants will actually “milk” the honeydew producers by stroking them with their antennae to get them to release the honeydew which is a high sugar, rich food source for the ants. Some ants and aphids have a symbiotic relationship in that the ants protect their aphid “cows” from predators in exchange for honeydew. The ant farmers tend their aphids, sometimes even chewing off their wings so that they cannot migrate. Sometimes, ants will even transport the aphids to suitable host plants and safe places to hibernate. As a result of this mutual admiration society, populations of both the honeydew producers and ants can soar. If the ants are pests and the honeydew producers are near buildings or people, pest problems can soar as well.
In some cases, you may be able to control an indoor ant problem not by treating inside at all, but by controlling aphids or other plant-sucking insects on plants near the building. Look closely at nearby plants, especially if you see ants moving up and down trunks or stems. Aphids usually cluster along the stem or on the undersides of leaves (on new growth.(Jh))
These plant pests are usually controlled by applying a systemic insecticide with a power or backpack sprayer. It is fairly straightforward pest control. You can also keep ants from reaching the honeydew insects in trees by applying sticky tape barriers around tree trunks. Note that most states require that you have an ornamental pest control license in order to spray for aphids and other plant-sucking insects.