And now, some small carpenter ants...

I haven't posted any ants for awhile. So here is a pair of little carpenter ants from the back yard:


Camponotus nearcticus


Camponotus caryae

Most people in North America think of carpenter ants as the big hairy black things that damage houses by chewing through older and dry-rotted wood. That's certainly true of Camponotus pennsylvanicus, the eastern black carpenter ant.

But the genus contains many smaller and less conspicuous species that nest in pre-formed cavities and plant stems, foraging for scraps and honeydew and generally bothering no one. The two pictured here are both abundant in our garden.

Researchers have started paying more attention to Camponotus in recent years, for two reasons.

First, it turns out that these ants' bellies are full of a bacterium called Blochmannia. Blochmannia are basically little Jesus bugs, converting water into wine urea into essential amino acids and allowing their host ants to thrive on diets where other ants flounder. So there's great potential for turning this ant/bacteria tryst into a coevolutionary model system.

Second, Camponotus lacks a metapleural gland. Why does this matter? One of the incredible things about ants- and one reason to study them- is their antibiotic prowess. Ant colonies inhabit warm, damp, moldy crevices, places where pathogens should abound. Yet these social insects are quite good at keeping their pests under control thanks to a battery of glandular secretions and associations with friendly bacteria. The metapleural gland is one structure suggested to have an antibiotic function, and how Camponotus survives without one will be an important consideration in studies of ant social immunity.


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I did not know that the sight of 'carpenter ants' does not automatically mean that the beams in one's house are being chewed into insect condominiums. So I guess I can hope that the ants hanging around my kitchen are harmless. I'm going to be at the mercy of the exterminator, however. If he claims that I've got destructive carpenter ants, I, not being an entomologist (let alone a myrmecologist), won't know any different.

The important thing to know about carpenter ants is they can't do much with good wood. They're not like termites. Rather, the ants move into wood that's already damaged, taking an existing problem and making it worse. If you have carpenter ants nesting in your house, it's often a symptom of a more serious problem.

But they'll also come inside looking for food, so just seeing them in your kitchen doesn't mean that they're also living in your house.

Exterminators are a mixed bag. I do know some good ones, but the profession attracts more than its share of snake-oil salesmen too. Be especially wary of anyone attempting to sell you a regular scheduled service.

Thanks. I'll keep all that in mind.

For that matter, they can be living in your house without actually being in the woodwork. Some years back, we had carpenter ants appearing in the kitchen, and upon investigation we found that they were nesting under the refrigerator. Not making galleries in the wood, but just nesting in a pile on the floor. It was a complete nest, with eggs/larvae/cocoons, and they seemed to be doing perfectly fine that way. Once it was vacuumed up, that was the end of the ants in the kitchen. So, before worrying about exterminators, I'd advise just following some of them back to their nest to see if it is something you can easily clean out yourself.

Is one of these ants called Joseph, the putative father of the Messiah ant?

This genus of ants is both fascinating and daunting to ant taxonomists. Clearly the lack of a metaeural gland is not maladaptive, as there is no other genus of ants that is represented by so many species in so many places. Some sort of Camponotus may be found in notoriously ant-inhospitable places like Patagonian grasslands, tropical cloud forests and boreal conifer forests, while many more (thousands of species, literally) inhabit almost every other terrestrial habitat in between these. There are desert species and even a semiaquatic one that forages in pitcher plants. The poorly studied faunas of most tropical regions support hundreds of undescribed species. And then there is the matter of the species-rich Old World "genus" Polyrhachis, which may actually be a branch of Camponotus. All I can say is YIKES!

By James C. Trager (not verified) on 16 Jun 2010 #permalink

Camponotus/Polyrhachis -- Anything like Strumigenys/Pyramica? What do you think?

By James C. Trager (not verified) on 17 Jun 2010 #permalink

Interesting that Camponotus and Polyrachis are related since they both host a diversity of Myrmozercon mites (or at least the Australian Polyrachis and Holarctic Camponotus do). However, the idea that there may be thousands of species of camponotine Myrmozercon needing description is enough to send me directly to a bottle of Australian shiraz.

Interesting article, Alex. Since ants are beginning to swarm, many people are seeing flying ants emerge. A lot of people ask us the difference between carpenter ants and termites, since both have wings and chew wood. You just have to know the difference in wings, body, and antennas. Carpenter ants only hollow out woods where termites eat it, both are very destructive.