Carpenter ants do not eat wood, they eat aphid and other sweet sugary excretions of insects. Aphids are their choice of food. Carpenter ants will care for, groom, raise and nurture aphids within their colony in special ‘aphid’ chambers; this is done to derive ‘honeydew’ from the aphids.

Carpenter ants cause damage to wood primarily due to nest construction. In other words, damage is only a result of their nest building efforts. As a general rule, carpenter ants do not damage wood, as heavily as subterranean termites, but given enough time and a large enough nest, damages can be severe. Carpenter ants have a habit of cleaning and polishing the galleries in the wood. The galleries are smooth in appearance and do not resemble the rough jagged appearance of subterranean termite galleries.

During the mining or excavation phase of nest building, carpenter ants make small ‘kick-out holes’ out of which all the trash and debris accumulated within the nest are tossed out. The garbage, which consists primarily of wood chips, insect particles, dead ants etc. often form small scattered piles which are often referred to by professionals as ‘frass’. If frass is found, then it should be carefully inspected to determine that it is carpenter ant frass and not the frass of drywood termites, as there is commonality between the two. The difference is that drywood termite frass is made up of their excrement and does not contain any insect particles, wood shavings, etc. Drywood termite frass only contains drywood termite faecal pellets, which if viewed under a magnifying glass resemble a small football with 6 concave sides. Any wood destroying insect damage should be a cause for concern and should be carefully evaluated.

Carpenter ant species reside both outdoors and indoors in moist, decaying or hollow wood. They cut ‘galleries’ into the wood grain to provide passageways for movement from section to section of the nest. Certain parts of a house, such as around and under windows, roof eaves, decks and porches, are more likely to be infested by Carpenter Ants because these areas are most vulnerable to moisture.

It has often been thought that in order to get rid of Carpenter ants, all one has to do is to get rid of the aphids. Aphids will attack all kinds of outdoor plants, so by spraying the plants you get rid of the aphids. Unfortunately, this often provides poor control since carpenter ants can forage several hundred yards looking for aphids.

Once the carpenter ant colonies have been located, they need to be treated with baits or non-repellent insecticides. Non-repellent means that the ants will not detect its presence and will not avoid it. In the case of baits, carpenter ants will be attracted to it, and hopefully feed on it. In the case of dusts or sprays, they will not detect its presence and not be repelled.

Many carpenter ant infestations are made much worse with the random application of sprays purchased at hardware stores. Overly noxious chemicals repel carpenter ants and if you spray something in order to repel them they will simply avoid it and move away from it. Sometimes, the ants will actually ‘split’ their colony into several new colonies in order to survive. This is called ‘satelliting’ or ‘budding’. If not treated appropriately a carpenter ant infestation can become a much bigger problem.

Some photos and information are provided by Bayer.