Inside Ant Nation
- By Joshua E. Brown
When you see a small ant heading for the sugarbowl on your kitchen counter, it’s likely Tapinoma sessile, known to myrmecologists everywhere as the Odorous House Ant or, simply, a sugar ant. (Odorous? Give it a squeeze to be sure. Smell like rotten coconuts or over-ripe bananas? Yep, you’ve got yourself Tapinoma sessile.) It won’t bite.
But if your ants are larger and black and appear from, say, a hole in the wooden sills in your basement, watch out. It may well be Camponotus pennsylvanicus, known to exterminators and dismayed homeowners as the Eastern Carpenter Ant. They subsist on rotting wood. With carpenter ants, pesticides are probably folly. Their nests can be hundreds of yards from the house.
All of this information — and much more about our region’s 130 species of ants — can be found in a new book, A Field Guide to the Ants of New England, co-authored by UVM biologist Nicholas Gotelli.
Ant identification for the people
The book, published by Yale University Press, is the first of its kind for New England. It combines a simple mini-guide (that was successfully tested by fifth graders with cheap hand lenses) — with more advanced keys (that were successfully tested with high school students) for identification work with a microscope, and are suitable for both amateur and professional naturalists.
Separate entries on each species contain color photographs, maps of where the ants are found, blurbs on each ant’s natural history — and spectacular illustrations by Elizabeth Farnsworth pointing out essential details to distinguish species: Is that Formica incerta, the Uncertain Ant? Or, perhaps, Formica dolosa, the Sly Ant? “Propodeal hairs, gastral pubescence, and body size distinguish them,” the guide notes.
Additionally, the book combines traditional branching keys with “a sort of matrix guide that compares related ant species side by side,” says Gotelli, “like a police line-up.” (And, yes, the authors provide straightforward instruction in just what “propodeal hair” is, and the other vocab needed to navigate the keys.)
There are also general chapters on ants in the New England landscape, basics of ant evolution and behavior, how to catch, collect and identify ants — and, at the end, a chapter on ant biogeography, Gotelli’s specialty, that explores the patterns of ant distribution across the landscape over time. “With climate change,” Gotelli say, “this is especially relevant as ant populations will move and change."
Writing the book you need
In the mid-1990s, Nick Gotelli was an experienced ecologist — but a beginning student of ant identification. He and Aaron Ellison — a researcher at the Harvard Forest and the lead author of the new ant guide — were starting a research project about carnivorous plants in northern bogs.
“When we started looking into pitcher plants, the most common prey was ants — so we had to start identifying all these ants that kept showing up in pitcher plant traps,” Gotelli says, “At the time, that was a hard thing to do.”
As Gotelli and Ellison labored to identify the many ants they collected, they found themselves turning to the only comprehensive treatise about the ants of North America, written in 1950 by William Creighton.
“Creighton is useable in some ways, but it’s dense going,” Gotelli says. “It’s not something you’re going to carry with you in the field.”
So Gotelli began to study ant identification himself, getting instruction from Stefan Cover, an ant expert at the Harvard Museum of Comparative Zoology, working closely with Ellison and other field scientists, taking a course on ants with famed naturalist E.O. Wilson, and creating his own field-guide-style notes.
“We ended up writing this book because this is the book we wish we had when we started our pitcher plant study,” Gotelli says.
Thank an ant
And the new book is a window into a world of small amazements, showing ants to be far more interesting and important than occasional household pests.
“Here in New England ants are the prime movers and creators of soil — not earthworms,” says Gotelli. They make about an inch of new topsoil every 250 years, Aaron Ellison says, and play a crucial role as one of nature’s diligent garbage collectors.
“Ants eat everything,” Ellison says. “Imagine, we’d be knee-deep in caterpillar carcasses if we didn’t have ants cleaning them up.”
Many of the region’s most spectacular woodland flowers, including trillium, bloodroot, fringed polygala and many violets, also depend on ants. “Ants are like the FedEx of the forest plant world. They carry seeds around, eat the small part that’s rich in protein and fats, and then they store the seeds — and essentially sow them — in the rich soil of their nests,” Ellison says.
Roll that rock
To create the field guide, the four authors — Ellison; Gotelli; Farnsworth, an ecologist at the New England Wild Flower Society; and Gary Alpert, a research associate at Harvard’s Museum of Comparative Zoology who took many of the photographs in the book — went on the road with a few students and colleagues for several rounds of what they call “blitz sampling.”
From Nantucket to interior Maine, the research teams would locate a field site, start a stopwatch, and begin flipping over rocks, digging around in rotten logs, and sifting through soil and leaves to collect an ant from every nest they could find.
Farnsworth admits that illustrating the guide — with more than 500 drawings — was her first truly close look at ants. “They used to be just the little critters that marauded my picnic,” she says. “But pick one up and look closely at it, or better yet, put it under a microscope, and you suddenly realize what gorgeous creatures they are.”
Other scientists and students caught wind of the project and began sending the team ants from habitats they’d missed. The authors also scoured every archived ant collection in the region, traveling to museums, universities, and personal collections throughout the Northeast and Canada. They ended up with just shy of 30,000 records of ant species from more than 100 different habitat types.
Fifteen of the ants in the book have not yet been formally named by science, including one species the authors note as the most difficult to track down: “an extremely small and shiny ant living below the sand in only a few habitats in Massachusetts,” according to Alpert.
The right bait
To start your own collection of ants, the book outlines the techniques and tools needed, including a small trowel, hand lens, vials, and, of course, bait. An index card covered with tuna fish works well, says Gotelli. “Or better,” he says “is a special cookie favored by ant biologists around the world. They’re called pecan sandies.”
Though the ants in your collection are likely sterile females, driven by instinct to serve only their secretive queen, and perhaps destined to live only a few days — “they’re more like the leaves of a tree than the tree itself,” Nick Gotelli says — nevertheless, “ants love pecan sandies.”
Portions of this story were reported and written by Clarisse Hart, Harvard Forest, Harvard University.