Carpenter Ants

Large black ants indicate a serious problem in your home

By: Sandy Feather ©2013
Penn State Extension

Q. We have an old poplar tree in our back yard. I have noticed large black ants active in a crevice in the trunk that I believe are carpenter ants. What can I use to get rid of them and keep them from feeding on this tree?

A. The black carpenter ant (Camponotus pennsylvanicus) is the most common carpenter ant species in the northeastern United States. Although they might be nesting in your poplar, they are not “eating” it. Research indicates that they prefer to nest in moist, decaying wood. However, they are scavengers, and they primarily eat other insects (dead or alive); tend aphids or other sap-feeding insects to feed on the sugary honeydew they produce; the juice of ripe fruit; and the sap from various trees. They nest in wood, but they do not eat it.

aphids on spirea
Ants  work in cooperation with aphids and will 'farm' aphids, moving them to the best feeding locations in exchange for honeydew. Check growing tips first for aphids since that is their favorite feeding location.


In their natural habitat, carpenter ants help with the decomposition of decaying trees. They nest in logs, stumps and hollow trees. They can become a problem in houses, particularly in wooded areas, when they come looking for food. If old or unprotected wood in the house has begun to decay, they may build satellite nests there to be closer to their food source. Carpenter ants do not usually invade sound wood.

The presence of a colony of carpenter ants in your tree is a strong indication that the tree has some type of interior rot that was caused by fungi rather than insects. I can suggest some products that can help control the carpenter ants and keep them from invading your house. However, you should contact a certified arborist to examine the structural integrity of the tree, because the interior rot should be more cause for concern than the ants. They are but a symptom of a more serious problem.

Low toxicity carpenter ant treatments

Dust formulations of diatomaceous earth or boric acid can be blown into the crevice of the tree to kill the ants. These products have no or very low mammalian toxicity and are safe to use around people and pets.



Using pesticides

Almonds and Pecans



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