Is a species endangered if you can't find it?

I'm sitting with two professors in an office in the Agricultural Science Building at the University of Idaho in Moscow, two of only a few people in the world who have had up close and personal experiences with the giant white earth worm of the Palouse.

I confess to them immediately that I am a complete ignoramus when it comes to worms, especially this worm. James "Ding" Johnson, head of the plant, soil, and entomological sciences department, assures me that when they tell me everything they know, I will leave almost as ignorant as when I arrived. Almost as ignorant as they are.

The giant white earth worm of the Palouse sounds like a hoax or a Bigfoot-style myth. But unlike Bigfoot, Driloleirus americanus has been found alive by scientists. The rare earthworm reputedly grows up to three feet in length and was once said to be "abundant" in the fertile rolling hills of the Palouse, a rich agricultural region encompassing some two million acres of southeastern Washington and northern Idaho. The Palouse was once uncultivated prairie with thick deposits of topsoil. The worms dig deep — maybe as deep as 15 or 20 feet — and they are white, like albinos, instead of the more familiar pink. They reportedly give off a smell like lillies and will spit at you if provoked.

Ding Johnson has probably seen more of the living worms than any man alive. In 1988, he and a graduate student named Paul Johnson (no relation) — both of them insect, not worm, experts — were looking for beetles at a place called Moscow Mountain, a peak that rises about 2,500 feet above Moscow, Idaho. Its forested slopes aren't like the smooth Palouse hills, and not the kind of habitat thought to be white worm-friendly. But the two Johnsons flipped over a chunk of moss and found six of the rare worms. Most of them escaped, but two were captured. Johnson has sinus problems and never smelled the lilly scent, but he says one did spit at him. Yes, worms have mouths. Anuses too.

The giant white's existence in sciences dates to 1898, when one was sent to experts for identification. Through the decades, there were stories and anecdotes about worm finds, mostly by non-scientists. That supposedly three-foot-long Palouse worm? Johnson says it was measured after a kid had been swinging it around like a lariat, so the truth of its size might literally have been stretched.

In 1978, a worm expert from Oregon found two. A decade after that was the Johnsons' bonanza. Then for 17 years, all was quiet on the worm front, until 2005, when a University of Idaho grad student named Yaniria Sanchez-de Leon, digging for worms in a remnant of Palouse prairie at a place called Smoot Hill, reserved for research by Washington State University, found one of the rare white creatures. Well, she found two halves of it, because she'd accidentally cut it in half with her shovel. It was an important find tinged with tragedy, kind of like finding a Sasquatch as road kill.

Nevertheless, the find generated excitement in the scientific community. The worm corpse was sent to the Northwest's foremost worm expert, the guy who found a couple of great whites in 1978. William Fender-Westwind is a true scientific character of the old school. Widely respected, he is no academic but a man who carries on a family tradition of amateur science. His mother is also a worm expert with a huge collection of specimens kept in a shed (claimed to be the largest such collection outside the Smithsonian). Her husband, a postman, was a recognized authority on soldier beetles.

Fender-Westwind is also obsessed with finding the great white worm's cousin, the giant earthworm of Oregon, which has also proven elusive in recent years. (Sierra magazine had an excellent profile of Fender-Westwind in 2003.) Despite his amateur status, Fender-Westwind is the go-to guy for earthworm answers. Ding Johnson says that worm and insect people stick together. "Neither is a social plus," he says. It was Fender-Westwind who autopsied Sanchez-de Leon's find and confirmed, in 2006, that it was indeed a great white.

It's now nearly two years since that identification, and no more Palouse worms have been seen. Not even in the places where they've been spotted previously.

Jodi Johnson-Maynard (no relation to either Johnson previously mentioned) is the other prof in the office. She is associate professor of soil and water quality at the university. As a soil biologist, worms are definitely her turf, and Sanchez-de Leon was one of her grad students. She pulls out a test tube about six inches long and hands it to me. It is filled with fluid and corked at the top. Inside floats the off-white corpse of a Palouse giant. It looks something like a pickled wax bean. It has a vertical seam, an incision from the autopsy. It looks crinkled and traumatized, no surprise given its violent, if accidental, end. For a major scientific enigma, it seems a bit forlorn. Even more so when you think that it could be the last of its kind.

Because this earthworm is so rare, little is known about it. Scientists don't know where it lives, how abundant it is (or was), what its life span is, how big it gets, or how it behaves. Researchers are working on hunches. Most earthworms you find now in the Northwest are non-natives. Yes, the wriggling pink thing in your garden is probably an invader from Europe, just like most of us. (Wasn't it the alchemists who said, "As above, so below"?) The giant Palouse earthworm may be the only native worm species in the Columbia River Basin, says Johnson-Maynard. If so, you have to be careful how much you infer about its behavior and characteristics from other worms.

And researchers' hands are somewhat tied for another reason. To truly understand a population of earthworms, you need to collect and study a fairly large sample of them. Finding great whites is obviously problematic. But also their likely habitat — remnants of the original Palouse prairie — are rare and fragile, too. You might endanger important prairie patches by going all-out to dig for worms, with no assurance of finding any. And it was digging that might have reduced the worm population in the first place. If they were truly abundant in the Palouse hills a century ago, 100 years of plowing might have been the coup de grace.

That, of course, is a major question. The U.S. Fish and Wildlife Service has declined to list the giant white Palouse earthworm as an endangered species. Palouse preservationists say they will appeal that decision. One told the Spokane Spokesman-Review that reluctance to act was "completely irresponsible." After all, waiting to get perfect knowledge of a species that's so rare and perhaps on the brink (if not over it) might condemn it to extinction.

The stakes could be high. The great white worm could become the spotted owl of the Palouse, impacting also adjacent areas where they've also been found, like Moscow Mountain. The implications for agriculture and development could be significant. Of course, the implications for the worm could be terminal.

It seems odd that you have to prove that an animal that's so hard to find is endangered, but rarity itself isn't proof enough. They could be thriving in unknown locations. Plus, if you don't know the worm's habits or needs, how can you manage the ecosystem to "save" it? Johnson-Maynard has been back to known worm sites to look for more great whites — a "worm quest," she calls it — and she plans to do much more investigating.

Ding Johnson says, "We don't know enough to say they are endangered." He adds, "Hunch is an important factor in our knowledge of this worm. ... When you're working on hunch, it drives scientists crazy."

"It does drive me crazy," confesses Johnson-Maynard.

I handed the worm vial back to her reluctantly. I felt as if holding on to it would have the talismanic effect of curing my ignorance. My hunch is that the great white will be a kind of scientific brain worm for a lot of people for some time to come. It'll take solving its mysteries to get its song out of their heads.

• Knute Berger is Mossback, Crosscut's chief Northwest native. He also writes the monthly Gray Matters column for Seattle magazine and is a weekly Friday guest on Weekday on KUOW-FM (94.9). You can e-mail him at mossback@crosscut.com.