Carpenter Ants

May 2005

Things I never thought I’d need to know.

In the 25 years that I have been in the pest control industry I’ve picked up some pretty strange information.

Fact is, if someone had told me in high school that I’d need to know any of this stuff I’d have thought they were crazy.

With spring fast upon us I thought I’d share some of the highlights about carpenter ants.  Maybe next time you’re entertaining friends you can wow them with some of these.

Did you know that even though carpenter ants live in solid wood they can’t eat it?  Sure enough!  Despite their size they can’t swallow solids.  They are so highly specialized that they have to rely on aphids and other sap feeding insects for most of their food.  Most of their foraging time is spent stroking aphids and scale bugs for honeydew.

A carpenter ant queen can live in excess of 40 years.  After mating males die. (makes me glad I’m not an ant!)  A carpenter ant colony is considered mature when it can produce new queens and males called “reproductives”.  This takes from 6 to 10 years.  When a colony reaches maturity the workers will start setting up additional nest sites called satellite or brood nests.  Well established colonies can have 10 to 12 brood nests.

A carpenter ants life starts as an egg which quickly hatches into a larva.  From egg to adult takes about 60 days.  Larva have Velcro like fuzz on the outside of their bodies and workers literally hang them on the walls of the nest. (Time was I could have wished to do that with my own kids to keep them out of stuff.)  Larva are completely helpless.  They have no legs.  Workers feed them by depositing nectar in a depression in front of their mouths.  Larva weave cocoons just like caterpillars.  The mature ant can not open its own cocoon and must be delivered by the workers.

Like most ants the workers are all sterile females.  Carpenter ant workers come in different sizes ranging from just under 1/4 inch to almost 1/2 inch.  Unlike termites, there are no soldier ants in the colony.  The largest ants act as tank cars to transport nectar.

Carpenter ants have been found nesting in some really strange materials.  They have a strong preference for soft wood and seem especially fond of cedar.  I personally have found these ants nesting in cardboard boxes, fiberglass and  foam insulation, compressed beauty bark, and creosote treated railroad ties.

A mature colony can have in excess of  20,000 workers but only about 10% of the colony forages.  The rest tend the nest.  They do most of their foraging between 10 pm and 4 am.  They may travel over 100 yards to food or satellite nests and will mow grass and move pebbles to keep frequently used trails clear.

So there you have it.  Enough carpenter ant trivia to fascinate your friends for about 10 minutes.  Hard to believe it took me 25 years to be able to remember all this.  Now if I could just remember where I put my keys.

April 2004

It’s spring again and after a winter of fasting and napping carpenter ants are waking up to go find some groceries.

For the most part carpenter ants are beneficial insects.  Their nesting activities help to return damaged trees to the soil.  Through their feeding they help control insect populations in the forest and their foraging and excavation helps aerate the soil.  A mature colony can consist of over 70,000 insects divided between a parent nest and 6 to 12 satellite nests, and be spread over several acres.  Carpenter ants have been known to forage for distances up to 100 yards from their nest sites.

Normally, carpenter ants nest outside in standing and hollow trees, stumps, logs, landscape ties, even railroad ties treated with creosote.  However, they have been found nesting in such diverse materials as foam and Fiberglas insulation, and between layers of tar paper and shingles.

Most species of ant are smaller than 1/4 inch but, carpenter ant workers average between 1/4 inch to 3/8 inch in length.  With some members reaching 1/2 inch in length and reproductives up to 2 inches including their wings.  Their color is black or black with some brown in the middle segment.  Their most distinguishing characteristic is their size.

These ants are adapted to nesting in solid wood.  Unfortunately, they can not tell the difference between a fallen log and your home.  Their individual nest sites can often contain over 20,000 insects and their combined activities can greatly weaken the structure of a home in a relatively short period of time.

Carpenter ants will nest in virtually any home.  Some homes have built in conditions that are more favorable to infestation than others.  Improperly installed insulation, missing vapor barriers, inadequate ventilation and other conditions which other wise raise the humidity within the structure.

Some of the more common signs of infestation are often over looked.  Frequently only a handful of the insects will ever be found foraging inside the house.  In the spring scouts emerge from the colony to establish feeding sites.  Once these sites are established you will seldom see the insects indoors.  Because carpenter ants feed on insects most of their foraging activities go on outside of your home.  Wood does not provide a source of food for them.

They sometimes make a scratching sound in the nest site similar to a bowl of Rice Crispies.  Piles of excavated sawdust are sometimes found close to nest sites.  However, this sawdust is not always evident as the ants will often deposit it in adjacent wall voids or other areas not readily visible to inspection.

Foraging trails along decks or along the exterior of your home are also signs that nesting activities are likely within the structure.

During the months of May and June, reproductive males and females will swarm from nest sites to establish new colonies.  Finding these large winged ants coming from any part of your home is a sign of well established nest site and professional assistance should be sought.

Because most over the counter materials make surfaces repellent and have extremely short life spans, ants tend to avoid them until they break down.  Effective treatment requires specialized materials, application tools, and treatment techniques not available to then average home owner.

In order to reduce our dependence on chemical control, a thorough inspection should accompany any treatment to help identify what favorable conditions should be eliminated to make the structure less vulnerable to re-infestation.

Feb 2003

Carpenter ants are an annual right of spring.  After a long winters nap they are starting to move around and many homeowners are already discovering these invaders.

Carpenter ants only damage wood in the process of building a nest.  They feed mostly on aphids and scale bugs (milking them for honeydew) and those insects play a large role in explaining carpenter ant behavior.    Because insects like aphids feed on sap they are slaves to what plants do and plants are slaves to the seasons.  So, it goes something like this,  Plants move their sap into their roots for the winter, aphids cant get the sap so they lay eggs or go dormant, aphids aren’t producing honeydew so the ants go dormant.

That brings us around to spring.  The sap returns, the aphids start producing honeydew and the carpenter ants wake up.

Now in nature many insects have built in alarm clocks but when carpenter ants nest in a heated structure this can get thrown off kilter.  If you see carpenter ants in your home before May it is usually because there is a nest in the building.  These ants are often still half asleep wandering around looking for water and sweets.  If you do nothing at all you will stop seeing the ants indoors as they find sap feeding insects and establish feeding trails outdoors.  This doesn’t mean they are gone, just foraging outside.  The colony will continue expanding in the building and if left untreated can do significant damage.
This time of year, aside from ants inside, you should be on the lookout for ants standing around on the foundation or decks.  They can often be detected at corners of the foundation.  Carpenter ants will avoid hiking over rough terrain and will trail along sidewalks, decks, landscape edging and garden hoses.  Utility lines coming to your home can also provide a pathway for them especially if they pass through tree branches.


If you find these ants this time of year (Jan thru April) it is too late for prevention.  Steps should be taken promptly to avoid damage.  Even though there are many products available over the counter for carpenter ant control, treatment for active infestations should be performed by trained, experienced people.  The most effective materials are not available to the general public and no one has figured out how to put experience in a can.

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