The Pacific Northwest climate is well suited for carpenter ants. It is not surprising that these wood nesting ants are the number one structural wood destroying insect pest in Washington State.
So how concerned should home owners be when they see these large winged creatures each spring invading their property?
Mature carpenter ant colonies have a main nest and one or more associated satellite nests. Main nests can be found in living conifer trees, stumps, landscape timbers, firewood, and most any sizable wood debris in contact with the soil. Main nests need wood with a high moisture content to survive. In contrast, Satellite nests can utilize dry wood such as the timbers of a structure. Most homes damaged by carpenter ants are a result of infestation by satellite nests.
Each spring, mature colonies send out thousands of new queen ants in swarms to establish new main nests. These black swarming ants, sometimes one inch in length, are called reproductives; they fly short distances before losing their wings and begin wandering for new homes. Only a small fraction of these winged reproductive ants survive to create new colonies.
Since these budding queens need wood with high moisture content, most well-maintained homes due not fulfill the moisture needs and are therefore not capable of being a main nesting site. In April and May, homeowners should not be overly alarmed when observing these large ants crawling in the landscape or occasionally in the house, especially if your home is routinely serviced for pest prevention.
In contrast, if you observe large numbers of winged ants clustering together inside your home or smaller, wingless black ants trailing in regular patterns inside or outside of your home, this may indicate an established carpenter ant satellite nest in the home, requiring an inspection by a qualified licensed pest management professional.
For those without regular pest control service, the month of May is an excellent time for an annual