The machaca, by contrast, which looks like a shad and is purported to leap like a steelhead, is not a carnivore. It's a...well, I don't know what the word for a machaca is. Revolting, maybe. It eats guano. Bird droppings, iguana droppings, people droppings. Drop it, a machaca will eat it. True, a machaca also eats fruit, leaves and other vegetal matter that falls into the water. But guano is a staple of its diet, and the idea of fly-fishing for such a creature is absurd.
Anderson wouldn't even admit what we were doing, knowing that most anglers feel squeamish when they learn the depths to which they have sunk in pursuit of the machaca. Without explanation, he had me casting a white fly to the base of some dead trees standing in the water, trees in which cormorants liked to roost. "Don't move the fly," he told me. "Just let it sit there." Sure enough, a machaca would hit.
Not that I was able to hook one. Their little mouths, filled with piranha-type teeth, which they use to chew fruit and seeds, seemed unable to swallow my poppers. So Pablo tied me some smaller ones at lunch. "The all-important bird ca-ca fly," Anderson said approvingly, holding one up to the light. "You ideally want something that emulsifies when it hits the water. Maribou or cotton imitates it best."
Lake Arenal, which is actually a reservoir 17 miles long, had one thing going for it that outweighed the success or failure of the fishing. It sits at the base of an active volcano of the same name. With a great thunderous rumble, Arenal, whose last catastrophic eruption was in 1968, belches several times a day, sending ash and soot hundreds of feet into the air. Usually the rim of the volcano is shrouded in clouds, but at night, when the sky tends to clear, you can see the red-orange lava trickling down the side of the volcano and, if you're lucky, the primeval display of magma shooting into the air.
On our last afternoon at the lake, after the weather had cleared, the volcano gave us a show. Pablo and I, numbed by hours of fruitless casting, dropped our rods in the boat and scrambled for our cameras. Suddenly, strangely, amid the rumbling there came a splash. A small female guapote, driven to suicidal impulses by the eruption, had viciously swallowed Pablo's Sneaky Pete popper. He put down his camera and reeled the poor thing in, an ash cloud billowing high in the air above him. It was our only fish of the day.
As for me, even the bird ca-ca fly didn't improve my sorry record. I got off the water still pitching a Costa Rican shutout.
I knew that the best, though, was still to come. The houseboat. Virtually unfished waters. Tarpon that we had been told reached nearly 200 pounds. Wily 40-pound snook. Endless runs of calba, or baby snook. The only negative was that we were entering the land of botflies.
I had first read about them in the Adventure Guide to Costa Rica, by Harry S. Pariser, in the section subtitled "Loathed by Humans." That would definitely be the botfly. The botfly's larva, inserted by female mosquitoes, matures inside human flesh. It isn't a pretty process. The lump each larva creates before hatching grows to the size of a goose egg. Pariser explains in his guidebook that there are several ways to get rid of the botfly worm before it hatches. One can, for example, tie a piece of raw meat over its air hole. The larva, which needs to breathe, eventually burrows out of your body and into the meat. Then you throw the meat away. No shrinking violet, Pariser suggests that another alternative "is to leave it to grow to maturity, giving you an opportunity to experience the transmogrification of part of yourself into another creature."
The odds of encountering this loathsome insect were not as remote as you might imagine. In a week in Costa Rica I met three different people who had been bitten, including Peter Gorinsky, the 55-year-old Guyana-born guide who had arranged for our stay on the Rain Goddess, a 65-foot houseboat that we had rented for three days of fishing on the San Juan River. He had been bitten by a botfly as a child. "It leaves a helluva hole in you, half an inch deep," he told me. "My older sister squeezed it—she thought it was a pimple or something—and this great big worm jumped out, and she fainted."
Gorinsky smoked a pipe with a big sweeping stem, like Sherlock Holmes's, and wore the continually bemused expression of someone who had seen and survived it all. He wasn't about to work himself into a lather over a botfly. "We've got a lot worse things than that, I assure you," he said and proceeded to list a few. For example, there was the bushmaster, a poisonous snake that will actually hunt a human being. There were peccaries—wild pigs that hunt in packs—which, according to Gorinsky, had eaten an American tourist a few years back as he slept in his sleeping bag. "All they found was the feathers," Gorinsky reported. There was a fly that carried malaria, another that gave you elephantiasis, and the dreaded eye fly, which lays its eggs in your tear duct. "Three or four days later you'll have a worm swimming around your eyeball."