Fredrik Sjöberg is a Swedish entomologist, and The Fly Trap, his completely charming memoir, is about science and the nature of unusual enthusiasms. (Death, too: Lots of hoverflies lose their lives in these pages.) How did he find his niche in this rarefied field? There are several ways to address this question—but the explanation found in the book’s first chapter is the only one that involves a rather well-known actor who didn’t mind urinating in front of dozens of strangers.

In the mid-1980s, Sjöberg was in his 20s and working as a stagehand in Stockholm. Curse of the Starving Class was that season’s production. Every night, as spelled out in Sam Shepard’s script, a certain male character was called upon to relieve himself onstage. The role was played by Peter Stormare, who a decade later would be the big blond murderer in Fargo. As Sjöberg remembers it, Stormare’s bladder was a breakout star, its owner destined for big things.

“Where I would wind up was less certain,” Sjöberg says, “but because it was I and I alone who was entrusted with the task of cleaning up this example of great acting—on my knees, in the dark, with a rag, hastily—it became clearer and clearer to me that my place was not, perhaps, in the theatre.”

For Sjöberg, finding his place meant exchanging an urban existence for life on a tiny island in the Baltic Sea. Runmarö is 15 square kilometers, and the year-round population is about 300. A thousand years ago, he says, it was probably inhabited by Vikings. On this small piece of land, Sjöberg spends spring and summer days catching flies and examining them through a microscope lens. He finds joy in incremental breakthroughs. “My fly was in any case the sixth one ever seen in Sweden,” he writes after identifying a locally rare species. “It was my first triumph.”

The Fly Trap, on its surface, is an item of narrow appeal. No disrespect to E.O. Wilson, but Americans aren’t typically clamoring for new writing about insects. What’s more, the specificity of Sjöberg’s work—he’s obsessed with hoverflies, ordinary-looking little creatures that are often mistaken for bees and wasps—would seem to further limit his potential audience.

But these are superficial qualities when compared to the book’s broader scope. Though he’s not so pretentious to say so, his real focus is the human imperative to find meaning in daily experience. It’s a subject he approaches in wry and disarming fashion.

As translated by Thomas Teal, Sjöberg’s prose is an unalloyed pleasure. In the most genial manner, he’s happy to tell his readers that they’re even more ignorant about the particulars of his profession that they might’ve imagined. “We are all familiar with the conventional image of the entomologist as a breathless twit rushing wildly across fields and meadows in pursuit of swiftly fleeing butterflies,” he writes. But this “is utterly incorrect when it comes to collectors of hoverflies…Running is not necessarily beneath our dignity, but it is any case pointless because the flies move much too fast.”

Which is why a few years ago he went and got himself something called a Mega Malaise Trap (named not for the state of mind induced by too many consecutive hours of fly-seeking, but for René Malaise, a pioneering Swedish entomologist and a hero of Sjöberg’s). It’s a big boxy thing, made out of netting. There’s a chamber for chloroform. Flies fly in, but they don’t fly out. He installed it in his backyard, and it’s enabled him to collect and identify more than 200 species of hoverfly. That’s a lot. Or maybe not. Depends how you look at it. There are 5,000 hoverfly species scattered across the continents, he explains, but fewer than 400 in Sweden.

Basically, what Sjöberg does most days is sit around. Not all entomologists are lazy, but judging by this book, lazy people can make pretty good entomologists. Waiting for insects to fill his trap, Sjöberg has plenty of time to think about why he finds his scientific subset so transfixing.

He says that the island’s population booms during the warmer months, and that it was during a conversation with one of these summer interlopers that he best articulated his reasons for choosing entomology: “I had simply told one of them in a moment of inspiration that my fly-collecting was a method of exercising slowness.” This was a smoke screen at first, he confesses, a way of sounding philosophical even as he was still working out why he’d decided to chase insects all day. But eventually a part of him came to believe it.

More recently, Sjöberg says, he’s come to think of himself as a kind of translator. Without at least some knowledge of your surroundings, he writes, the untamed world can resemble “an impenetrable body of text in a foreign language. So the best answer to the question of why I collect hoverflies is, ultimately, that I want to understand the fine print in the only language that’s been mine for as long as I can remember.”

But The Fly Trap isn’t just a series of artful ruminations on the timeless quest to understand the natural world (although that would be enough, wouldn’t it?). Sjöberg is a genuinely funny guy.

“I used to say that I was a writer,” he recalls, “but all the women on the island felt so sorry for my wife that I started insisting I was a biologist instead.” He drolly describes a close friend who happens to be a poet and an amateur dung beetle fanatic as “(a)n odd fellow, certainly, but no worse than the others” with similar entomological fixations. And he tells a hilarious Abbott and Costello-esque story about a confusing encounter in which he and a stranger kept talking past one another until they realized that one was using the word “yew” and the other was hearing it as “you.”

A man who studies insects is surely a devoted conservationist, so it makes lot of sense when Sjöberg takes a moment to excoriate developed nations whose “environmental politics are themselves a natural disaster.” But there’s no heavy-handedness here. Indeed, The Fly Trap is such an ardent, informed and sustained brief on behalf of the planet that a plea for this or that piece of green legislation seems unnecessary. The very existence of this subtle book is a powerful argument for vigilance.