In July of 2004, I was walking in the pines of Arizona’s Santa Catalina Mountains. There were some Aspen Trees growing near the trail, and I saw that its leaves and stems were covered in ants.
As I looked more closely, I found spectacularly beautiful black ants tending the aphids on the stems of the Aspen. Carpenter Ants!
As with most species of ant, I have a hard time identifying Carpenter Ants with any degree of certainty. After struggling with various identification keys, I believe these ants to be Camponotus modoc, a fairly common ant.
I don’t know what species the aphids were.
These ants were large. I was used to needing to squint to see ants. I didn’t need to squint to see these ones!
The aphids were laying flush against the aspen stem – they were not raising their hind ends into the air as aphids often do.
The ants were then laying over the aphids, often parallel to the aphids’ bodies, and licking them.
Watching the ants was very enjoyable. There was an air of concentration about them, they did not seem to pay me any mind at all as I photographed them. Usually it’s difficult to get ants into the frame of a photograph – but not in this case.
The ants were also eating aphid honeydew off of the Aspen’s leaves, not in the physical presences of aphids.
My suspicion is that the aphids produce so much honeydew that, at times, it falls onto the leaves below and dries, making a sort of “ant candy”. I wonder if the aphids produce more than the ants can consume at once, or if perhaps this overflow is from the aphids’ production when the ants are not active. Maybe in cooler weather, or at night?
I suspect that the common-place nature of this ant/aphid/tree interaction makes us become blase about the miracle of it. We’ve got trees producing sugars, aphids eating the sugars, and ants tending the aphids as ranchers tend cattle. It’s miraculous.
And this is ignoring all of the other complexities of this system that we don’t see immediately. The interconnections of the Aspen roots, the soil fungi an their connections and interconnections, the gut symbionts in the ants and the aphids, the predators and parasites of the ants and the aphids…it’s really quite mind-blowing.
Sources:
AntWiki.org’s Camponotus modoc page. I cannot say enough good things about the AntWiki.org site.
Mackay, William P., and Emma Mackay. 2002. Ants of New Mexico: Hymenoptera : Formicide. Edwin Mellen Press. ISBN-13 : 978-0773468849. This is a fabulous book.
