Wednesday, May 26, 2010

Carpenter Ants: Marching One by One

It happens every year. The heat of summer arrives and the ants are on the move. I usually first see them in the evening when I take the dog for his walk, and then again the next morning. The apparent migration lasts for several days. Who are these ants, where are they going and what are they doing? I had to know.

First I needed to know what kind of ant I was encountering. I headed out last night with my camera and attempted to photograph some of these insects. It seems that whenever I need a close-up of a plant, the wind blows. Likewise, when I need a close-up of an insect, it insists on continuously moving… rapidly. Still, determination was on my side and I finally captured a couple images that were good enough for ID.

I suspected these were carpenter ants simply because of their size. My insect field guide has images of two carpenter ants: the western carpenter ant and the black carpenter ant, the latter of which is common here in the east. But, my ant is not totally black; it has a red thorax. I needed a better ID source.

Once more, www.bugguide.net came to the rescue. Within half an hour of posting my photos the answer came back: Camponotus noveboracensis, the New York carpenter ant. This is a nearctic species, which basically means it is found in the northern parts of North America. How lucky are we New Yorkers to have a carpenter ant named after us?

When it comes to carpenter ants, most of us have an understandable aversion, for they can be the bane of the homeowner’s existence. When I bought my house, the insurance company went over details of my policy with me over the phone. One comment that the agent made has always stuck with me: we don’t have termites up here, so we don’t have to worry about that. But she said nothing about carpenter ants.

Termites eat wood; carpenter ants do not. Still, carpenter ants are not called “carpenter” for whim alone. These large ants live in wood. A newly fertilized queen seeks out a damp, rotted stump or log to set up home. Damp, rotted wood is soft and easier to excavate. She finds a suitable site, enters, breaks off her wings, and commences the business of creating a colony: excavating a nest and laying eggs.

Because she has no workers to help her out with this first batch of young, the queen has to take care of them all by herself. She never leaves the nest to forage, so when her eggs hatch into hungry larvae, she feeds them from reserves in her own body. Because this food is rather Spartan, these larvae end up pupating into rather runty adults, which are known as “minors.” Once they are all grown up, these minors live to serve their queen: they forage for food, further excavate the nest, and raise the queen’s subsequent broods.

Adults born from later broods are more robust (and thus called “majors”), thanks to the foraging efforts of the workers (which are sterile females). When they are full adults, they join the workforce as additional workers. Slowly the colony builds up. By the time the colony is about four years old, there may be 400 individuals populating it.

It isn’t until the numbers swell to about 2000 (six to ten years) that the colony is ready to divide. At this point the queen lays eggs that hatch into winged females and winged males, both of which are called “reproductives”. These hormonally active adults are produced at the end of the summer and spend the winter at home with Mom and all their sisters. When the first really warm weather of the following spring arrives, they head out in search of mates (ah-ha!). After mating, the males die and the newly inseminated females, now queens in their own rights, seek out stumps or logs to call home.

So, it turns out that the (mostly) winged ants that I’ve been seeing on the roads are the reproductives. Knowing that once the colonies are large enough to expand and form satellite colonies, which are often in our homes, I don’t feel too guilty when I step on any individual that gets too close to my foot.

But when do they become problems in our houses? As mentioned above, the queens seek out soft damp wood because it is easier to excavate. If your house has damp conditions, you may be a target for carpenter ants. But even if your house is high and dry, well-ventilated, free of foundation plantings and woodpiles, you could still have carpenter ants, for satellite colonies are not as fussy as the queen in the parent colony. No, these industrious individuals are just as happy to take up residence in solid wood – the timbers of your home. Here they excavate extensive galleries that enable them easy access to other parts of your house, to food, to friends and family.

If you see piles of sawdust collecting about your house, you should be suspicious. You should also look for trails in your yard, for these ants are a lot like people, building highways for repeated use and maintaining them for ease of travel by keeping them free of debris and vegetation.

They also like sweets. While insects and other arthropods make up a large part of the carpenter ants’ diet, they also collect the sweet exudate, or honeydew, produced by aphids. And they seek out rotting fruits.

Eliminating carpenter ants from your house can be a real chore, for you have to eliminate the parent colony in order to have any real success. And if you have carpenter ants, you really should look into getting them under control, for they can seriously damage the structural integrity of your home.

Still, in their rightful place out in nature, carpenter ants serve a useful purpose by helping turn old, rotting trees into sawdust that eventually becomes part of the soil of the forest floor, creating a continuously self-renewing and balanced ecosystem. And it’s hardly the ants’ fault if we provide them with such lovely abodes in which they can take up residence. We just need to build better and learn how to make our homes less appealing to our small carpenter friends.

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Ellen Rathbone

Ellen Rathbone is by her own admission a "certified nature nut." She began contributing to the Adirondack Almanack while living in Newcomb, when she was an environmental educator for the Adirondack Park Agency's Visitor Interpretive Centers for nearly ten years.

Ellen graduated from SUNY ESF in 1988 with a BS in forestry and biology and has worked as a naturalist in New York, New Jersey, and Vermont.

In 2010 her work took her to Michigan, where she currently resides and serves as Education Director of the Dahlem Conservancy just outside Jackson, Michigan.

She also writes her own blog about her Michigan adventures.





2 Responses

  1. wendyusuallywanders says:

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