Tiny detectors of hidden delicacies:
searching for truffles with the mouches à truffe

by Tom Fiorina on January 13, 2010

A recent sunny, January afternoon, with a clear blue sky and temperatures hovering above freezing, got me thinking about a similar January afternoon just over ten years earlier. My wife and I had recently purchased a walnut farm in the Périgord region of southwest France. I didn’t want to raise a family in a Parisian apartment, so all of our vacations over a three-year period of time were spent with agents of the SAFER, a French agency that is responsible for rural land planning. It buys and sells farms to keep them from being turned into housing developments, golf courses, or other non-agricultural purposes.

We loaded the contents of our apartment into a small rental truck, and, along with our nine-month-old son, made the 800-km (500-mile) drive to our new home that the SAFER had helped us to find—a 22-hectare (almost 50-acre) farm with 600 walnut trees. In reality, the trip was more like a step back several centuries in time. Sheep outnumbered the hamlet’s year-round population, which almost doubled with our arrival. We loved the beauty and solitude, the warm welcome our new neighbors extended to us, and the experience of living in the French countryside (OK, maybe I appreciated that more than my wife, who was more concerned about the inadequate heating in our 200-year-old stone house and its effect on our baby’s health).

I won’t say that it was truffles that clinched our decision to buy this property—I’m certain that we would have bought it even without them, but when René, the owner, mentioned to us that there was a truffière (a truffle field) on the farm, my ears immediately perked up.

As a long-time fan of gourmet food magazines, I had read many articles about truffles. However, none of my cooking or dining experiences had ever included this revered member of the mushroom family that can cost up to €1,000 a kilo (around $750 a pound).

Moving to France in 1990 got me closer to truffles. When window-shopping at Fauchon’s famous gourmet food shop in Paris, I would press my nose to the glass and try to imagine how the black truffles in the small, jewel-like containers smelled. But that’s as close as I could get–until now. I had been bugging René for months about truffle hunting—through the harvest of eight tons of walnuts in the fall, through the hunting season when the hunters chased wild boar and stag through our fields (occasionally leaving a wild boar leg or a part of the hindquarter of a stag on our porch for me to trip over), through the preparations for Christmas, which included selecting and cutting one of the pine trees that René and his wife Yvonne had planted years earlier.

Finally, on the last day of the year, René said that we were going truffle hunting the following week. This was early in the truffle-hunting season, but I guess that he had gotten tired of my pestering him. The day was sunny and clear, with no breeze and the temperature around
40° F–perfect truffle-hunting conditions, according to Rene. After putting on my overalls and boots, I gathered together the tools that he said I would need: an old screwdriver for unearthing the truffles and a plastic bag for carrying them home.

We set off on foot for the truffle patch, which sat on a plateau high above the walnut trees. I had noticed, when Rene arrived, that he had not brought a pig or a dog, the two animals that I had read were used in hunting truffles. This had me perplexed, but I resisted asking how we were going to locate the truffles. I knew from prior experience that, given Rene’s fondness for discussing any topic, any questions would risk delaying our hunt even further.

Rene had planted each of the farm’s walnut trees more than 30 years earlier when he and Yvonne bought the property. Each tree was like a child to him, and he could recite a story about nearly every one of them–how that tree had lost a limb in a particularly violent storm or how this tree was a favorite resting spot for the wild boar and stag that roamed the property.

He and Yvonne were like our surrogate parents. As neophyte farmers, we relied on them to explain each detail of the farm’s operation. And despite having sold the farm because of their advanced ages, they helped us with the walnut harvest, working from morning to night. It was not until we had lived in the region for some time, and I learned how closely people guard the secret of truffle patches, that I realized the level of their generosity. In fact, one day I discovered during a casual conversation with them that the man who had sold them the property had never disclosed the fact that there were truffles there. It was not until years after the purchase–years during which the man had undoubtedly returned annually to harvest the truffles–that they stumbled upon the truffle patch.

As we walked, my mind wandered to the Lascaux cave with its world-famous prehistoric paintings in the village of Montignac, just to the west of us. I wondered whether the artists who painted this Paleolithic Sistine Chapel might have enjoyed a truffle with the wooly mastodons and other prehistoric beasts that they hunted 17,000 years ago in this region. It’s almost certain that the Romans, who came to fight the Gauls here 2,000 years ago, knew of these underground delicacies. They, like the ancient Greeks before them, valued the truffle for its taste and rumored aphrodisiac qualities.

My thoughts of artistic Cro-Magnons and love-seeking Romans were interrupted as we reached the truffle patch. The casual hiker would undoubtedly pass right by it. The most prominent sign was a tall oak tree that, unlike the other surrounding oaks, still had its leaves hanging from its branches even though it was early winter. On either side of the oak tree were the characteristic rings of “burnt” grass, or brûlés as they are called in French. These rings are caused by the symbiotic relationship of the truffles and the oak tree’s roots, which inhibits other plants from germinating by monopolizing all of the surrounding nutrients and water. The framework for this symbiotic relationship is a mycelium, an underground network of hair-like filaments that supports the truffle’s growth.

Truffles, which can be anywhere from the size of a marble to a man’s fist, grow in loose, humid, sun-soaked soil that is rich in chalk or limestone. Although there are at least thirty different varieties of truffles, the two most interesting, from a gastronomic perspective, are the black Périgord truffle, Tuber melanosporum, and the white truffle, Tuber magnatum, found primarily in Italy’s Piedmont region. Which truffle variety is the tastiest is a subject of much nationalistic concern. According to culinary experts, black Périgord truffles have a musky, nutty, earthy flavor, while the white truffle combines these flavors with a slight garlicky taste.

The truffle trees on our property were undoubtedly remnants of the extensive plantings of oaks to cultivate truffles that occurred in the late 19th century following the outbreak of the Phylloxera disease that decimated vineyards throughout France. This golden age of truffle production resulted in a harvest of 2,200 tons in 1890. Today, with almost all of the rural population gone, the harvest is between 25 to 150 tons per year.

Traditionally, truffles were hunted with a female pig, or sow. Sows are naturally attracted to truffles because the truffle’s odor resembles sex pheromones given off by the male pig. Sows, however, present the truffle hunter with a variety of challenges. Being heavy, they are difficult to transport to the truffle site. They also do not navigate steep or uneven terrain very easily. But the real problem begins when the sow discovers a truffle. The combination of a tasty truffle and pheromones is irresistible to the pig, which explains why truffle hunters in old photos are always shown holding a large stick that they used to try to beat off the sow before she ate the truffle. Dogs are now more commonly used to hunt truffles, with mixed-breeds reputed to be the most effective.

As it turned out, all my research and knowledge about hunting truffles with pigs and dogs was not going to be put to use. Rene, selecting a long, thin branch from a bush and instructing me to do likewise, explained that we were going to use les mouches à truffes (“truffle flies”) for our truffle hunt. This technique, he explained, relies on the fact that a number of species of flies lay their eggs above truffles. Once the eggs hatch in early spring, the tiny larvae burrow down to feast on the truffles that, by then, are beginning to decompose. The branches that we had selected, he said, would be used to gently probe the brittle winter grass that covers the flies. The tiny flies, I was soon to learn, are transparent, making them difficult to locate.

Explaining that any hint of a shadow would alert the flies to our presence, Rene instructed me to keep the truffle patch between me and the low winter sun at all times. He then demonstrated the proper truffle-fly-hunting technique: moving forward in a low crouch, the truffle hunter pokes and probes the grass with his stick. The objective is to watch for the slow ascent of flies that have been driven aloft by the stick. When disturbed, they fly for a few feet, alighting quickly on a blade of grass or a plant.

Sniffing for truffles, while my then not-yet-two-year-old looks on (“Daddy, why’s your nose dirty?).

Once a fly is sighted, the hunter attempts to identify its point of origin. Usually, a few dead leaves or sticks will have to be cleared from the spot. Once the ground is cleared, the truffle hunter kneels down and, using a digging tool, slowly and carefully removes the soil. It’s important to search thoroughly and to break up large clumps of earth, Rene said, as a soil-covered truffle can be overlooked easily. At this point, the truffle hunter may attempt to locate the truffle by using his or her nose. Doing so means getting dirty, as you need to lie flat on your stomach, with your nose right down in the hole. Inhaling deeply through the nose, like a bloodhound seeking the scent of its prey, the hunter tries to catch the distinctive scent of a truffle. Another technique is to grab handfuls of dirt or a stone from different parts of the hole. Soil or a stone that has lain close to or against the truffle will have captured some of its odor and will draw the hunter that much closer to the prize.

Occasionally, when the brûlés are particularly effective and the ground vegetation is not dense, the truffle hunter may even observe flies in the process of laying their eggs. The flies stumble across the ground, seeking to position themselves directly above the truffle. In frantic, back-and-forth movements, they locate the truffle with sensory organs found in their antennae. Sometimes, two flies will arrive above a truffle at the same time. Things can then get violent, with the flies tussling and rolling about until one grows weary and leaves to find another truffle.

After searching unsuccessfully for several minutes, I spotted a glimpse of movement up ahead and slightly to my right. My stick had stirred a fly from its resting place. Not having seen clearly where it had been resting on the ground, I crouched down and hoped that it would return quickly from the branch where it had alighted. My patience was rewarded several minutes later when the fly returned to a small, bare spot on the ground, right at my feet. Soon afterwards, the fly began to crawl, first to the right, then back towards me. This seemed to be the spot, as the fly appeared to be ready to start laying her eggs.

Shooing away the fly, I followed Rene’s instructions and cleared the spot of any leaves or rocks. I then began to dig slowly with my screwdriver. A screwdriver is preferred over a shovel or trowel, he explained, because there is less chance of damaging the truffle with any overzealous digging. A shovel’s blade, he added, would also cut through the mycelium’s delicate fibers, which would hinder the future development of truffles. Digging carefully, much like a mine detector probing for explosive devices, I gently uncovered the soil in layers. After I had dug down around four inches without any indication of a truffle, Rene had me lie flat on my stomach and place my nose down into the hole. And, there it was: distinct, from the smell of grass, damp earth, cool rocks and other woody odors, I smelled, for the first time, the unmistakable odor of a truffle.

Black gold.

After sampling several handfuls of earth from different parts of the hole, I was able to determine the approximate location of the truffle by the intensity of its odor. Focusing on that area, I began to uncover the dirt slowly, using my fingernails as much as the screwdriver. Finally, I unearthed a truffle about the size of an egg, its black, pockmarked surface barely discernable from the lumps of dirt surrounding it. I savored the full effect of its aroma for a second, whispered a silent thanks to the fly that had led me to it, and set off in search of another truffle fly. When my plastic bag contained three other truffles like the one that I had just found, we returned to the house tired and much dirtier. Following Rene’s instructions, I brushed the dirt from the truffles and placed them in a tightly closed glass jar in the refrigerator to keep until they would be added to an omelet or a pasta dish, or slipped under the skin of a roast chicken or turkey. Whatever the dish, the addition of a truffle magically transformed its flavor.

Since that truffle hunt, I now have newfound respect for flies, and I’m not so quick to grab a fly swatter when one buzzes me during a picnic. I am also thankful to René, who taught me how one of nature’s tiniest and most unassuming creatures could be used to uncover such an exceptional delicacy.

René, unfortunately, is long gone. So is that property. I have kept the two tins of truffles that Yvonne kindly prepared of some of the treasure that I found that January day. I doubt that truffles, unlike wine, improve with age, and the tins that contain them are starting to show their age. It’s like a good bottle of wine; you always want to keep it for some special occasion. The next time that I prepare a foie gras or a turkey, however, I think that I’ll use them. And we’ll make certain that we drink a toast to René.

To René (holding another of my sons), who taught me all I know about walnuts and truffles.

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Per-BKWine January 14, 2010 at 11:37

A wonderful story. That’s really how it is! It’s a magic experience. (A bit like fishing crayfish at night in a Swedish forest, for those of you who know – but better)

I think you underestimate the price of truffles. It’s too long since you left Paris perhaps. It’s rather like 2000€ per kilo.

And I’m not sure about those tins of truffles you have… One truffles hunter I met said that they don’t keep very well when fresh, perhaps two weeks. If you wanted to keep them longer than that he suggested deep freezing (!) them. But I guess the ones you have are in a conserve. Probably not the same thing as fresh but hopefully still delicious!

I thought it also might be fun with some more illustrations to the story so I put up some photos: a truffle fly (yes!), truffle hunt, truffles and a few others.

You can find the truffle pictures here:

tomfiorina January 14, 2010 at 12:38

Per, thanks for your comment and those wonderful photos that you put up, although my heart goes out to that truffle fly ;-). You’re undoubtedly right about my being out of the truffle market too long–we should have kept that property, for more reasons than the truffles… I’d like to try night-time crayfish fishing in Sweden sometime, but it sounds eerily similar to snipe hunting or cow-tipping (at any rate, I imagine that a good set of thermal underwear is an essential part of the gear that is needed for this). And the truffle tins probably contain better memories, than truffles, at this point.

Truffle Hunter Italy January 14, 2010 at 14:55

It sounds just like Gustaf Sobin’s “The Fly-Truffler”. One Italian truffle hunter I know used to use flies to find truffles before he trained his first truffle dog -at the age of 12!

tomfiorina January 14, 2010 at 14:59

Thanks for having brought that book to my attention. I’ve added it to my Amazon Wish List. I see from your email and URL that you’re an experienced “tartufi” hunter from Umbria. Curiously enough, before we purchased our walnut farm in the Périgord, we looked at farms in Umbria. Beautiful country… That farm-hunting trip would be a good article. We had contacted a guy named Nando, who had advertised an agency called Umbria Realty in the International Herald Tribune. He didn’t realize how much Italian we understood (my wife, in particular, is quite fluent because she speaks Corsican), and he kept calling his secretary (probably a cousin of his) on his mobile phone (this was in the early 1990s when mobile phones were still quite rare), telling her to call him regularly so that it looked as if he had a lot of clients or was extremely in demand. He took us to see a number of what he called, in Italian, “stupendous ruins”; because of our budget and interest in renovating old houses, we wanted, what we call in American English a “fixer-upper.” Periodically, we’d visit some place that didn’t have two stones that were still upright, and, when I would try to get a look at the interior, he would scream: “non va più lontano! (“Don’t go any further!”), as he feared that the floor would cave in. He also took us to see a 13th-century tower (which we later discovered was owned by his family) that was around 5-meters square by 15 meters in height. It would have made a great elevator shaft, but as a home it left a lot to be desired. Too bad that the agency seems to have gone out of business, as a quick search of the Internet showed, as I would love to see Nando again.

Christine January 14, 2010 at 22:41

Thank you for refreshing my memories of the Perigord. My time with M-A at Madame Archer was one of the most unusual and educational vacations that I shared with your family. Great photos….Almost “yoga-esc” Chrissy

tomfiorina January 14, 2010 at 22:48

Thanks, Chrissy. That was a good trip. We just ate some confits from Mme Archer last week (this wasn’t 10 years old; it was purchased in 2009). It brought back a lot of good memories.

Heide January 15, 2010 at 00:33

Beautiful..Here’s to Rene and an art that requires more patience than I have.
Thanks again for a great experience.
Best to you and your family,

tomfiorina January 15, 2010 at 10:44

Thanks, Heide. My best wishes to you and your family as well. Too bad that you don’t live closer. We’d share a truffle together.

tammi k. January 15, 2010 at 21:57

thanks for the fantastic article. although i doubt i’ll ever put the methodology of truffle hunting to use, i highly enjoyed being transported to an idyllic walnut farm on the french countryside….i loved it so much i had to share with my friends on facebook….

tomfiorina January 15, 2010 at 22:28

Thanks, Tammi. I’m glad that you enjoyed the article. Two other people who wrote comments about this article run truffle hunts in Italy and France (you can go to their websites by clicking on their names). Those are with dogs, not flies, but it would certainly be an interesting experience nonetheless. I’ve never hunted truffles with a dog, so I may try that myself someday. Maybe I should start training our black lab, Enzo, now…

Laurie January 16, 2010 at 04:30

Dear Tom,
Interesting article, and I loved seeing the photos, especially of the one where you are looking like a bloodhound. Too bad, brother-in-law John wasn’t there, I could picture him being down there sniffing, also..

tomfiorina January 16, 2010 at 10:36

Thanks, Laurie. Tell John that we can always use another good nose here. And using Palmiers (French puff-pastry cookies) as a reward sounds like a good deal to me;-).

Robert Giorgione November 21, 2010 at 20:59

A mouth-wateringly delicious article. I love truffles and have some great wine recommendations on http://www.robertgiorgione.com
The epicurean odyssey continues…

Tom Fiorina November 21, 2010 at 23:48

Thanks, Robert. I will definitely look at your wine recommendations for truffles.

Johanna N. June 23, 2011 at 16:48


Just wanted to ask if any of you might know of electronic truffle detectors in the US or Europe?
Thanks in advance for any replies. (I know it’s an awkward question).

Tom Fiorina June 24, 2011 at 07:32

Sorry, I don’t know of any such devices. A quick search on Google, however, turned up a lot of results–so maybe there will be one available someday. Do you have truffles in Hungary?

Johanna N. June 28, 2011 at 20:33


Thanks for your reply. Yes, we do have truffles in Hungary.
I am only doing some search on behalf of someone who saw a tv programme about such a device. I found some articles, too and they were quite helpful.
Do you think it is easy to train a dog to search for truffles? I have never tried it before, but I guess you can be lucky if you try early enough.

Tom Fiorina June 29, 2011 at 21:15

I’ve only worked with truffle flies, Johanna, but I’ve heard that training a dog is not that difficult. You have to start when they’re young, have a great deal of patience, and find a dog with a good nose. Let me know how your truffle research progresses.

FQ2o July 8, 2013 at 04:37

very nice post, i definitely enjoy this fabulous website, persist with it.

Tom Fiorina July 8, 2013 at 09:07

Thanks for your comment.

Peter Nagy January 4, 2015 at 19:26

Thank you for this excellent article, I really enjoyed reading it.

Having been a passionate — yet amateur — truffle hunter quite some time ago I sometimes saw specimen of the fly you’re referring to in your article. I however never had to rely on them given that I had a well trained truffle dog back at the time (that has unfortunately passed away since). There was, however, another insect I commonly encountered, the small, red bug of the species Leiodes cinnamomea — feel free to google it up. Whenever I saw this bug during digging it was always a giveaway that the truffle is right there somewhere.

All that took place in Hungary and the truffle I gathered was always T. aestivum, yet it appears that the same bug is also native to France, Italy and Spain and that it feeds fondly — just as the fly — on T. melanosporum as well.

Sniffling right into the hole for the scent of a truffle is a technique I also occasionally used but probably not as often as your neighbour Rene. After all, I always had my dog there with me to assist. Whenever she noticed that I was stuck she eagerly helped me out by touching the ground with her own nose leaving a small, wet spot right where she knew I should proceed. It was real fun. 🙂

Just by sniffling around while walking in the right woods I found it sometimes rather easy to pick up the scent of the truffle confirming that I am probably on or rather close to a good patch.

As a final remark, I have just established my own truffle farm of one hectare using common oak as host trees. It is a Périgord truffle (T. melanosporum) farm, yet as this species is not native to Hungary, it may eventually never become productive — only time will tell.

Tom Fiorina January 5, 2015 at 10:02

Peter, thanks for your comment. I wasn’t aware of Leiodes cinnamomea (the “truffle beetle” that you mentioned). I wonder if they were present in our truffle patches, and my preoccupation with the “truffle fly” kept me from noticing them. We have a five-month-old labrador with a pretty good nose. I’m sure that it is much more interesting hunting truffles with a dog, rather than an insect, but unfortunately the walnut farm in the Périgord was sold long ago. Good luck with your truffle farm in Hungary. I hope that it will produce truffles one day.

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