Do we have Carpenter Ants in Maine and how do you get rid of them?


 Do we have Carpenter Ants in Maine and how do you get rid of them? 


Katherine Garland, Horticulturist

Yes, we primarily have two species, the Eastern black carpenter ant and the red carpenter ant. If you suspect you have some, we always welcome you to send us a few clear pictures so we can confirm the ID. Here’s an excerpt from the management section in our bulletin on carpenter ants. Click here for more information describing the characteristics and biology of these insects.

“The presence of large ants usually is the first sign of infestation. Coarse sawdust is a sure sign, but it is often difficult to find the nest. At night, turning on a light to observe ant activity around a sweet that has been left out may reveal an “ant line” to and from the nest. Sometimes the insects’ activity can be heard in walls. Tapping areas suspected of harboring nests may produce a hollow sound, and some excited ants may appear. Carpenter ants tend to be most active between 10 pm and 2 am.

A household aerosol spray containing pyrethrins can be used as a flushing agent. Direct the spray into cracks, crevices or holes. This will excite the ants so that they will run out, revealing the source of the infestation.

Usually, there is no need to tear walls open to eliminate a colony unless repairs are to be made anyway to a faulty or damaged structure. Drilling holes into suspect areas such as walls, sills, joists, underneath sinks, behind appliances or below outside siding can aid in the penetration of insecticide into the nest. Only the nest, if you can find it, needs to be treated. Materials such as boric acid, silica aerogel, bifenthrin, cyfluthrin, deltamethrin or permethrin can be used for treating nest sites. If you cannot locate the nest, but manage to leave an insecticide dust nearby, workers may carry the poison into the nest on their feed. After treatment, holes can be caulked and touched up with paint, leaving no visible damage.

There is no need to treat walls, floors, counters, cupboards, etc. Any insecticides should be used only as crack, crevice or hole treatments. This reduces human and pet exposure and avoids contamination of other areas. Dusts are most effective and easier to get into wall voids or behind items.

Quick kills are achieved when insecticide is placed in the ants’ nest. Crack and crevice controls usually take longer because it takes time for workers to carry enough insecticide into the nest to kill the colony. Ant baits such as those containing boric acid or liquid borax (e.g. Terro Ant Killer II) labeled specifically for carpenter ants can be part of a control program.

 Place baits out of reach of children and pets!