Ants can increase problems with honeydew producers such as soft scales, mealybugs, whiteflies, and aphids. They can protect these pests from natural enemies and move them around the plants, enhancing an infestation. A long line of ants going up a tree trunk is a clue that there may be a problem. Ants also can disrupt the biological control of some non-honeydew producing pests, such as mites and armored scales.
Deny ants access to plant canopies by pruning branches that provide a bridge between buildings, other plants, or the ground, and applying sticky material to trunks. Do not apply material directly to the bark of young or thin-barked plants or plants that have been pruned, as the material may have phytotoxic effects. Wrap the trunk with a strip of fabric tree wrapper duct tape and apply the sticky material to it. Remove the old wrap or tape and apply new material as needed to prevent girdling injury to the trunk.
One way to control ants is to use sweet but toxic baits. Baits in the form of ant stakes or traps can be an effective way to get poison into the nest. Ants are attracted to the bait and carry portions of it back to the nest where it is given to other ants. Place traps where ants can easily find them but away from small children. Control with baits may take several weeks or more to be complete. Effectiveness varies with ant species, bait material, and availability of alternative food. Argentine ants are the easiest to control with baits.
For more information on managing ants, see the Ants Pest Note.
Ants tending woolly aphids