An Encounter with a Fer-de-Lance

by guest writer S. C. Morgan

Costa Rica is home to many of the world's deadliest snakes, including thirteen species of pit vipers. The largest of these is the bushmaster (Lachesis muta), but it is the fer-de-lance (Bothrops asper), or terciopelo, that locals fear the most.

When we first moved to Costa Rica our neighbors repeatedly warned us about them. They believed if I merely saw a man bitten it would bring bad luck. I wasn’t keen on seeking one out, but sometimes a snake is just where it is. 

One February morning back in 2007 my husband and I drove to the county seat to pay our garbage bill. I dressed casually in shorts and a tank top for comfort in the tropical heat. Alan parked our old, dependable Jeep pickup in front of the municipal building and I asked if he wanted to go with me. Getting the predictable answer, I left him there and walked in. Ten minutes later, I was back. I climbed into the truck and started to tell him about my success over bureaucracy. 

Then something caught my eye. 

Right in front of my bare legs was a huge snake. It was sliding out of a hole where the hinges of the open door met the body of the truck, its head the size of a fat banana. At first it arrowed straight toward me, sliding its thick body over the bottom hinge of the door. Then it folded back against itself. I was sure it was about to strike. I saw the triangular shaped head. Two heat-sensing pits above its nostrils. Brown hash marks on its dark gray sides. Terciopelo.

 What happened next took less than five seconds, but it felt as though the snake and I were frozen in time. Our eyes locked. My mouth tasted of metal. I remember thinking, How could there be a goddamned snake in our truck?  A nanosecond later I croaked, "Snake…snake….SNAKE!"

It looked annoyed and waved about in midair.  It flicked its tongue, searching for an escape. I sucked my stomach in, drawing my chest and face as far away as possible. My knees were so close I was afraid it would use them as a landing pad, and the console between the two seats blocked me from moving over into the driver's seat. I needed an exit. Now.

I jerked my legs around to get out. The snake drew back. Alan watched helplessly as it struck twice as I whipped past.

Once out, I slammed the door, hoping to crush it in the hinge. Too late. Alan saw it roll over the hinge and retreat inside the fender wall while the door closed. He estimated it was about three feet long and three inches thick. Huge. 

It is amazing how much can happen in a short period of time, how fast a snake can move. Looking back, I am sure it was a warning strike. If it used all of its incredible force or extended itself fully I know I would have been snake bit.

A nurse with ER background, I had read that the average venom injected by terciopelo is about 100mg, although they can inject up to three hundred. Fifty is a fatal dose for humans. I did not know at the time— not sure it would have calmed my frayed nerves any—that adult terciopelo often save their venom when striking animals larger than they can eat, because it takes a full day to regenerate their venom. Small consolation. Terciopelo young inject the full amount, having not learned this valuable lesson yet. Pit viper venom is hemotoxic and complications with clotting factors is the number one cause of death; unless the patient is given antivenin the blood becomes more and more coagulated, the body begins to throw clots to the coronary arteries, and cardiac arrest is the final outcome.

So, there we were in Bribri with a venomous snake in our truck. Granted, it was not in the cab, at least not that we knew. Alan gingerly opened the driver’s side door and popped the hood latch. Then he raised the hood. We both peered into the bowels of the motor. No snake. I kept one eye on my sandaled feet in case it wiggled out from underneath. 

“I’ll go get some repellent,” I said, and ran across the street to buy a can of Off at the grocery store. Snakes have a strong sense of smell and I reasoned it wouldn’t care for the spray. Alan opened up my side of the truck. Again, no snake. He sprayed into the dark hole and slammed the door. We waited. No snake emerged. 

We discussed the anatomy of our truck. The snake must have wiggled up the wheel well– last night? Two weeks ago?– and found an entry between the exterior paneling and the inner wheel well. The only exit was how it got in, or the way it tried to get out.

"So, if we keep the door shut it can’t get at us, right?” I asked.

“Unless there are snake sized holes in the firewall of the dash,” Alan said.

“Great.” I suddenly became acutely aware of  how much rust the old Jeep had accumulated after twenty years in the tropics.

“Let’s go get something to eat, ” he said. “Maybe it’ll leave while we have lunch.” I wasn’t very hungry, but I wasn’t eager for an hour-long ride back home.

After hearing about our escapade, the proprietor of the little cafe kept a close watch on the truck. No snake. Customers offered up advice about how to deal with our dilemma. One suggested we spray with insecticide. I explained I’d already used mosquito repellent. “It is very dangerous to have a snake in the car,” he said. The understatement for all time.

“Well, we can’t stay here all night," Alan said after lunch. "I guess we’ll take a chance.” I was ready to leave the keys in the truck and walk away. Maybe put a sign in the window that read: Free.

The drive back was uneventful. Alan said I rode like a nine-year-old schoolgirl, sitting ramrod straight, my knees bent, and feet tucked as far away from the dash as I could get them. At one point the bead seat cover brushed the back of my calf. I almost jumped through the open window.

We never saw the snake again, but Alan did find its skin. When it left, it used a hole in the frame to peel it off. The locals tell us terciopelo are more aggressive right after they've shed their skins. The one that rode with us to Bribri was enough for me.

(Gordon's note: The terciopelo is also called the barba amarilla or tommygoff. It's one of the lanceheads, the snake genus responsible for more human deaths in the Americas than any other.)

Photos by S. C. Morgan, with special thanks to Clodomiro Picado Institute.


  1. What a ... well, let's not say "wonderful" story, but it is a solid reminder that we live in nature rather than apart from nature. Something I wonder: is it possible for a private citizen to keep a snake bite kit with anti-venom on hand? My wife is allergic to shrimp in food and our physician has written a prescription for an "epi" pin for her to carry.

  2. Gary, my understanding is that it's possible, but difficult. Antivenin needs to be refrigerated, and it's expensive. (How expensive depends on the snake, but we're talking hundreds of dollars). Traditional antivenins also carry a significant risk of anaphylactic shock, a potentially fatal complication. (Of course, people like your wife already have to be prepared for that emergency.) I'm told that newer antivenins now in use in the US don't carry such a risk of anaphylaxis, but I don't know how widely used these antivenins are. (Later this morning I'll be linking an article that mentions this very idea. Apparently some people in the United Arab Emirates do carry antivenin because of the saw-scaled viper, which is even more dangerous than the terciepelo.)

  3. Correction: That article from the UAE will actually run Wednesday, July 13.

  4. Very cool experience, if scary... I am from Mexico and the fer de lance is known here as "nauyaca real"; it is responsible for most of the fatal snake bites in this country. Not only is it highly venomous but also extremely bad tempered and it often bites more than once. A friend of mine who's the chief snake handler in a zoo has told me that even though he has worked with king cobras, Gaboon vipers and mambas, he still prefers to deal with those than with the fer de lance.


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