Guest Post: Burrow Hole Blues

For today’s post, I am pleased to introduce nature writer and guest blogger Sharman Apt Russell. Epitomizing the increasingly important role of citizen scientists in conservation and natural history study, Sharman recently engaged in a year-long study of the Western red-bellied tiger beetle. Her experiences studying this little-known insect form the basis of her latest book, Diary of a Citizen Scientist. Chasing Tiger Beetles and Other New Ways of Engaging the World. With writing that is both humorous and whimsical, Sharman highlights the extraordinary scientific contributions being made by ordinary people. Of course, tiger beetles and citizen science are two subjects right up my own alley, so I’m avidly reading my own copy right now. I hope you’ll pick up a copy too (see ordering information below). The following excerpt from the book was kindly provided by the author.

When you’re a hammer, everything looks like a nail, and when you’re looking for the larval burrow hole of a Western red-bellied tiger beetle or Cicindela sedecimpunctata,  you see a surprising number of holes you’ve never seen before. Usually they are not the right size or shape, but you think about them anyway because suddenly you are curious: who lives inside all these holes?

Western Red-bellied Tiger Beetle adult. Photo by Cary Kerst.

Western red-bellied tiger beetle adult. Photo by Cary Kerst.

In Arizona and New Mexico, the Western red-bellied tiger beetle is a common and abundant species that comes out in June, before the summer rains, to congregate around ponds and ditches and river banks. For the last few years, as a citizen scientist, I have been trying to fill in what we don’t know about this insect, which includes what kind of habitat the females lay their eggs. Once these tiger beetle eggs hatch, the tiny larvae start digging vertical burrows, the entrance almost perfect circles in the dirt that increase in size (1-3 millimeters) as the larva goes through three stages or instars and enlarges the burrow. But where are those blankety-blank burrows? Does this beetle oviposit close to water or as much as a half mile away, like Cicindela marutha, the aridland tiger beetle? What kind of soil do Western red-bellies prefer?

Western Red-bellied Tiger Beetle larva. Photo used with permission.

Western red-bellied tiger beetle larva. Photo used with permission.

My entomologist-mentors David Pearson and Barry Knisley, coauthors of A Field Guide to the Tiger Beetles of  the United States and Canada, want to know the answers to these questions, and I’ve promised them that I would find out. So far, for three years, I’ve broken that promise, looking up and down the Gila River in southwestern New Mexico without success. About this time, in late fall, I start to give up, thinking that the larvae have closed their tunnels in order to overwinter.

On one last walk along the Gila River, a few holes remain to tempt me.

A number of almost-perfect circles in the dirt, eighty feet from the riverbank where I have seen hundreds of adult Western red-bellied tiger beetles congregate in the summer, are too large but still irresistible. Hole after hole, nothing lives there now. Instead something probably emerged months ago.

Tiny perfect circles in the dry upland grass are promising. Tiny ants are passing by, and I can see how the fiercely predacious tiger beetle larvae might lunge from such a hole to catch one of these ants. Then I notice how often the ants are marching into these holes, which are obviously their nests.

Other holes near the trail I am walking have turrets or small mud chimneys. I don’t bother to look inside these, knowing they were not built by the Western red-bellied tiger beetle—whom I have reared up in terrariums. (Yes, I have seen their larval burrow holes, just not in the wild.) Possibly these are the old nests of digger bees whose turrets prevent parasitic flies from flipping their eggs into the burrow to hatch and devour the bee larvae. Similarly, Williston tiger beetles construct turrets like this on salt lake beds in eastern New Mexico.

Closer to the Gila River, in dry cliffs that once marked the river’s channel, I see lots of cicada emergence holes and what I think is the home of a tarantula. Tarantulas start their burrows as spiderlings and live there a lifetime, as long as ten years if male and twenty-five if female. This entrance is over an inch in diameter and covered with a light veil of silk that keeps in humidity and carries vibrations down into the foot-long tunnel with its J-shaped chamber. About three inches long, fully-grown tarantulas hunt beetles and grasshoppers and other small prey at night. Their defense against the foxes and coyotes and raccoons who like to eat them are irritating abdominal hairs that fall off easily and get into a predator’s eyes or nasal passages. (Coatis have learned to dislodge those hairs by vigorously rolling the spider back and forth along the ground.) Most people who walk around the Southwest become fond of tarantulas and think of them as lucky, much like having a roadrunner cross your path. I always give a glad mental shout—hey, neat! a tarantula!

Along the river now are signs of beaver chewing on tree trunks; perhaps a den is nearby. Southwestern beavers tend to make bank dens rather than lodges, a bank den having several entry tunnels with one above the high water mark. Its single inside chamber is about two by three by three feet. Other holes I’ll see on this walk might be made by gophers or ground squirrels, pocket mice or grasshopper mice. Collared lizards and whiptails use the holes made by other animals but occasionally dig their own burrows with a half-inch, half-moon shaped entrance. Wintering snakes also borrow someone else’s hole and sometimes den communally, rattlesnakes and bull snakes and whipsnakes all together. Burrowing owls modify the holes they find by lining the interior with feathers, food debris, and horse and cow dung. A Field Guide to Desert Holes says blandly, “This may be to disguise their scent to predators or as decoration.” Similarly, skunks borrow burrows or make their own, decorating them with a strong musky odor. Coyotes only use dens when birthing and raising pups, often on a hillside or bank, the hole taller than wide. There are a few large mysterious holes near my house that I like to think were made by a badger, a prodigious and powerful digger.

I guess we just see the top half of life. Somewhere, I know, the larvae of the Western red-bellied tiger beetle are bedding down now at the bottom of their tunnels (at least 15 centimeters deep), quiescent, waiting for winter to pass. In the spring, they’ll emerge again to catch prey. Eventually they will pupate into adults, congregating in June along the Gila River. Their life cycle is still a bit of a mystery. Maybe I’ll solve that mystery next year—or the next or the next.  In the meantime, I could be doing worse things with my life than looking for holes.

Western Red-bellied Tiger Beetles mating. Photo by Mike Lewinski.

Western red-bellied tiger beetles mating. Photo by Mike Lewinski.

About the author
Sharman Apt Russell lives in the Gila Valley of southwestern New Mexico and teaches at Western New Mexico University and Antioch University in Los Angeles. Her books related to entomology include Diary of a Citizen Scientist: Chasing Tiger Beetles and Other New Ways of Engaging the World (Oregon State University Press, 2014) and An Obsession with Butterflies: Our Long Love Affair with a Singular Insect (Basic Books, 2005). Her work has been widely anthologized and translated into over ten languages. For more information, please go to her website and consider signing up for her infrequent newsletters www.sharmanaptrussell.com.

Ordering Information
Title: Diary of a Citizen Scientist
Author: Sharman Apt Russell
Publication Date: October 2014
Price: $18.95 paperback
Description: 224 pp., 6×9 inches
ISBN: 978-0-87071-752-9
Ordering: Available in bookstores or by calling 1-800-426-3797. Order online at http://oregonstate.edu/dept/press

© Sharman Apt Russell 2014

About Ted C. MacRae

Ted C. MacRae is a research entomologist by vocation and beetle taxonomist by avocation. Areas of expertise in the latter include worldwide jewel beetles (Buprestidae) and North American longhorned beetles (Cerambycidae). More recent work has focused on North American tiger beetles (Cicindelidae) and their distribution, ecology, and conservation.
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2 Responses to Guest Post: Burrow Hole Blues

  1. perfect shots! I love the pics

  2. Pingback: Morsels For The Mind – 07/11/2014 › Six Incredible Things Before Breakfast

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