I have been getting questions about ants hanging around trees recently. These large, dark brown to black ants can range from ¼ inch up to ¾ inch for a queen. Carpenter ants seek soft, mushy wood to excavate for nests but may move into sound wood as the need arises. They do not feed on wood as termites do but remove what is needed to build galleries in which to rear their young. The sawdust is ejected and forms piles that can help locate a nest. Carpenter ants feed on honeydew given off by aphids, other insects, animal remains and household food scraps. As stated before, they do not feed on wood.
Carpenter ant infestations in trees normally begins in an area where the wood has already started to decay. These insects are not directly harmful to the tree but are making use of wood that is already starting to decay.
Control is normally not warranted unless the tree is acting as a bridge for the ants entering a home or other structure. Carpenter ant nests in structures must be controlled. If control is deemed necessary, locate the nest by looking for sawdust piles and then the area of entry where the wood is rotted. Use a pyrethroid such as permethrin (Hi-Yield 38 Plus Turf, Termite & Ornamental Insect Spray; Bonide Eight Vegetable, Fruit & Flower Concentrate; Bonide Eight Yard & Garden RTS and Hi-Yield Garden and Farm Insect Control) or cyfluthrin (BioAdvanced Carpenter Ant & Termite Killer Plus) that is labeled for trees or other structures.
