Carpenter ants: the other unofficial state insect of Michigan

Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.

There seems to be some disagreement about our state insect. Officially we don’t have one, but unofficially we seem to have two. An internet search suggests that both the monarch butterfly and green darner dragonfly are the leading candidates to be the number one bug for the state. I am not a big fan of cute bugs. Sure, the monarch is pretty, but seven other states claim it as their state insect, which makes monarchs ordinary and borderline boring in my mind.

Dragonflies on the other hand are among my favorite insects. They are primitive, fierce predators. The larvae are exceptional. They have really cool mouthparts and their mating behavior can only be described as bizarre. Their physical beauty is unmatched. Just visit the Dragonfly Society of the Americas website at http://www.odonatacentral.org/, to see what I mean. Plus, there’s that old wives’ tale about them sewing people up (hence the common name ‘darner’). No, sir, there is not much to dislike about dragonflies, but as a state insect I can think we can do better.

About twenty years ago, I received a call from someone who was putting together a list of state insects. This person said his research failed to find one for Michigan and would I happen to know what it was.I told him that I would have to get back to him on that. It took only a few phone calls to determine that Michigan did not have a state insect. I was embarrassed for all of us.


The black carpenter ant: my vote for state
insect. Photo: Clemson Univ. - USDA Cooperative
Extension Slide Series. Courtesy of forestryimages.org

I called him and told him what I had found out. He said no problem and then asked me to pick one. I was honored of course and without hesitation, I named the black carpenter ant, Camponotus pennsylvanicus. After all this time, I remain convinced in wisdom of my decision. Carpenter ants may not be gorgeous, but they are hard working – just like Michiganders. They are highly social animals – just like us. Ants are very advanced; they are at the pinnacle of insect evolution. Based on the number of phone calls I get about them, I have concluded that nearly everybody in this fine state has encountered them. I don’t know if this make them popular, but there is no doubt that many of us share our homes with them. Shouldn’t our state insect be one that we keep so close to us? Forget pretty, cohabitation is a much higher standard. The fact that they are considered a pest should be secondary.

Carpenter ants are one of the largest and most common ants in Michigan. Most of the people I talk to about carpenter ants think they eat wood and are serious wood destroying pests. Not true, no house in Michigan has collapsed because of carpenter ants. Unlike termites, they only nest in wood and do not eat it. They will bore into wood, but the wood they chose to bore into is wet and well on its way to becoming rotted. When they nest indoors, they are a symptom of a water problem and water problems in structures are far worse than carpenter ants. One does not have to drive very far out in the county to see old abandoned houses and barns that have caved in because their roofs have rotted away because of water infiltration.

When talking about carpenter ants, the first thing I ask people is whether or not they see carpenter ants in their home during the winter months when carpenter ants are not active outside. If they see ants during the winter, it is a very strong indication that a colony of carpenter ants exists inside the building. Finding them indoors during the summer does not necessarily mean they are nesting in your house; they may just be coming in from outside. When they do nest indoors, they prefer an enclosed space that remains wet or damp, more or less, or a permanent basis. Carpenter ants are attracted to excessive moisture conditions around windows, doors, showers, bathtubs, dishwashers, leaky pipes and drains, and under leaky roof shingles or roof vents. They have also been found in dry areas such as hollow-core doors and false beams and in foam insulation.

They seem to love foam insulation. My canoe, which I store outside, is home to a colony of carpenter ants. It has foam insulation inside of both ends to keep it from sinking when it’s tipped over in the water. Every time I move it, a steady stream of foam bits sifts out of both ends. Then without fail, a parade of carpenter ants carrying eggs, larvae and pupae comes scrambling out of both ends, no doubt perturbed at me for disturbing them. My canoe is 30-plus years old I doubt that it floats anymore, thanks to my little friends.
The presence of winged carpenter ants inside the home during the summer, does not by itself, mean you have a carpenter ant nest in your home. Winged ants are the reproductive forms of the colony and usually issue from the colony in late spring. They drop their wings soon after mating and begin to search for a suitable nesting site. They commonly enter structures, but only rarely do they succeed in finding a nest site and most winged forms die before establishing a nest.

However, the presence of winged carpenter ants during the winter months means several things. It means there is a colony nesting in the house, the colony is thriving and has been there for at least two years.

The best method of controlling an indoor colony of carpenter ants is to locate the nest and treat it directly with a persistent insecticide registered for indoor use. Finding the nest can be difficult since many of the ant’s favorite nesting sites are inaccessible. Begin looking in the rooms where the greatest numbers are found, and observe where they go or come from. Carpenter ants are nocturnal and are most active at night. Carpenter ants are very tidy housekeepers and quickly remove wood shavings, food debris and dead co-workers from the nest area. In many cases, this nest debris accumulates in basements beneath the nest area, so look for accumulations of coarse sawdust and dead ants along and on top of basement walls and in spider webs. Wood shavings do not always mean carpenter ants. Once a friend of mine asked me to help an old friend of his who thought he had carpenter ants. The man showed me some piles of wood shavings on his basement floor. I looked up and noticed that some new wiring had recently been pulled through holes drilled through the floor joists. The electrician hadn’t swept up. The shavings were from the holes that he had drilled to run the wire through. Oops!

To help find the nest, try mixing some grape jelly with one teaspoon of ground up dried pet food and use this as a bait to get them feeding and carrying food back to the nest. Put a teaspoon of the bait on a jar lid or piece of foil and place it near where you see the ants. Hopefully, they will use the bait and lead you to their nest area. Keep in mind that carpenter ants are most active at night, so be prepared to do some late night ant watching. Also, carpenter ants nest located under leaky shingles are not easily detected until the old roof is torn off. Every roof that I have replaced over the years has had carpenter colonies in areas where the roof leaked.

Most importantly, be sure to make any repairs, if necessary, to keep the area dry once a carpenter nest has been located and treated. Commercially prepared ant baits are available, but I don’t know how effective they are at controlling carpenter ants. They are probably more effective in the winter when the ant’s favorite foods are not available. One internet supplier of carpenter ant baits is http://www.doyourownpestcontrol.com/carp.htm.

Be sure to read and follow all the instructions and safety precautions found on the pesticide label before using any pesticide.

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