Singing Ants

I stopped along our road to checkout curled leaves on a young ash tree and once again found lots of ants crawling over the leaves to protect aphids inside and collect their honeydew.  After touching the leaves I saw the ants tapping their abdomens against the leaf repeatedly like a woodpecker in reverse.  I sent this video to James Trager for his interpretation.

  - University of Florida

He tells me that these are carpenter ants and they are communicating with their neighbors with sounds called stridulation. It turns out that they can make a lot of sounds but not in our hearing frequency, as discussed in Shhh, the Ants Are Talking!  Watching closely I can now see that the abdomen isn't actually touching the leaf.  Wild About Ants describes how the sound is made this way:

"On one segment of the gaster there is a patch of tiny ridges like a file. On the petiole is a curved ridge called a scraper. The ant produces a squeaking sound when she rubs them together, which known as stridulation. You can produce a sound in a similar way by rubbing a craft stick across a comb."

We don't know exactly what message the ants were sending. They may be communicating food sources, danger of possible predators or even "Smile for the old guy with the camera." What ever it was, the stridulation frequency increased when I disturbed a branch.

Inside the curled leaf

Frequently you will see an ant crawl inside one of the curled up leaves, probably for a honeydew snack. You can see what goes on inside the leaf in this video as there are multiple generations crawling over each other while feeding on leaf juice. The sight is enough to give a gardener the hives.

One week later I could see the aphid colony was thriving under the protection of the ants.  Since they deliver 3-4 live birth babies a day with no predators their population had outgrown the leaf curls and were now covering lots of leaves and petioles out in plain site.  As I was taking this photograph, my arm brushed a branch and the ants gave me a personal dose of their predator protection.  After those little ant jaws penetrated my skin I thought I heard her stridulating, bragging about the unmentionable words she made me say.