Field Journal: A Close Brush With Stinging Army Ants

Leeanne Alonso looks for ants in leaf litter on a 2009 RAP survey.

For 20 years, field scientists participating in CI’s Rapid Assessment Program (RAP) have been exploring some of the world’s most abundant, mysterious and threatened tropical ecosystems; to date, they’ve discovered more than 1,300 species new to science. Entomologist and RAP Director Leeanne Alonso describes a day in the field on a recent RAP expedition in the forests of southern Suriname.

I sit on a rotting log in the quiet forest, looking for signs of movement. Nothing but branches falling and a few small birds swooping past. In the movies, filmmakers portray the rainforest as teeming with dangerous animals — snakes slithering down tree trunks, ocelots prowling after monkeys or peccaries, and scorpions at every turn, waiting to sting you. These animals are definitely out there, but they’re hard to find and even harder to see, blending in with the dense vegetation and hiding out in caves and crevices.

My RAP colleagues are out in the forest right now looking for these elusive animals, putting out traps of all kinds: small boxes with oat-peanut butter bait to tempt the mice and opossums; mist nets to catch birds and bats in flight; camera traps to take clandestine photos of large mammals and birds that pass by. Just last night a camera about 200 feet [61 meters] from our camp took a photo of a jaguar walking along our trail. I’m sitting very near to that spot right now. The animal probably moved on when it smelled humans; then again, it could be watching me right now, so I keep a lookout for yellow eyes within the sea of green.

Traps do some of the work for us, but we find most species by actively looking for them. The RAP bird team walks for miles at dawn and dusk to record and identify the birds by their songs. The herpetologists hunt for frogs and snakes along creeks at night, following the frog calls to find their hiding spots. Botanists measure out plots and count all the trees and estimate their mass. They have it easier — the trees don’t run away and are easy to find. However, they can be harder to identify, as accurate identification requires finding the flower or fruit.

I look down, where the action is — at least in my mind. The leaf litter — the layer of dead and decaying leaves, twigs and fruits that covers the soil — will become the organic soil of the forest from which the trees and shrubs obtain their nutrients. The hot, humid climate causes the leaf litter to decay quickly so that carbon, nitrogen and other nutrients are transferred to the soil where they are quickly taken up again by the trees. This process of soil formation provides the foundation for all plant life, including the crops that sustain us.

Within this leaf litter is a whole world of fascinating, tiny creatures that we know very little about. Springtails, mites, amphipods, beetles, pseudoscorpions, and of course my favorite creatures: ants. I get out the tools of my trade: a trowel, a sifter and tray, forceps, vials filled with ethanol, and leather work gloves. I look around me for a spot with some good litter — it should be fairly thick, not too wet, with a fair number of leaves and twigs that look like they’ve been there for a while. Litter at the base of a tree or around exposed tree roots usually houses a good variety of ants.

I find a spot and scoop up some leaf litter, twigs and soil into my sifting tray. I use gloves and trowel to avoid being stung by stinging ants, scorpions, wasps and other creatures, as well as to avoid being jabbed by a spine from a palm or another plant. I watch for movement among the sifted litter in the tray — ants are restless and always on the move. I spot a large black Pachycondyla running across the tray, dashing to make its escape. I look closely for the tiny ants — little specks walking slowly over the soil particles. To me, these are the real gems — the species that perhaps no scientist has seen before.

As you might guess from my profession, I usually have a good relationship with ants. However, just last night I had a bad experience with my little friends. I had put up my tent while it was still light and then went to help prepare dinner. When I returned to my tent in the dark and got in for the night, I heard a crinkling sound in the far corner of my tent.

I grabbed my headlamp and shone it in the corner. A small swarm of ants had chewed holes in the floor of my tent and were beginning to stream inside. These were a species of Neivamyrmex, a nocturnal army ant that emerges from underground during the night to forage. I had unfortunately placed my tent right on top of their hole. I was fortunate that I had returned to my tent when I had; if I had been a bit later they would have been all over my tent — in my sleeping bag, in my clothes — and it would have been almost impossible to get all of them out. These ants sting something fierce; if they had reached me in my sleep, it would have been a true nightmare.

When I return to the camp, I show the other RAP scientists that ants I’ve found. They in turn show me beautiful creatures they have found: frogs, katydids, fishes, plants and bats. Some people may think we are just cataloguing the diversity of life on Earth before it’s gone so that we’ll have something to remember — that it’s too late for most of these species. I hope that’s not the case; I can’t just sit by and watch that happen. So I head back to the forest to look for more ants, taking a local forest ranger and a university student with me. They also play an essential role in protecting these forests, and we need all the help we can get.

Leeanne Alonso is the director of CI’s Rapid Assessment Program (RAP). To learn more about 20 years of RAP achievements, check out the new book “Still Counting.” Read other posts in our series commemorating RAP’s 20th anniversary, or check out the new RAP book “Still Counting.”

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