The Fly Trap (9 page)

The Riddle of Doros

I have made one exception, only one, from my rigid rule about collecting only on the island. One of the 202 fly species in the rows in my cabinet is a borderline case. It was the satellite man who brought it.
Eristalis oestracea,
the big shaggy one.

A pretty fly, capricious in its behaviour. Perhaps it’s had a hard time surviving, because its business plan since immemorial times, maybe millions of years, has been, like a sheep in wolf’s clothing, to plagiarize the troublesome gadfly (
Oestrus ovis
). They are truly very similar. A cow can hardly tell the difference, and neither can anyone else. The problem is just that the gadfly was eradicated from this part of the world a long time ago. And so the protective similarity vanished. For this same reason, we stand in openmouthed wonder at other insects so bizarrely designed that not even a surrealist on drugs could have made them up. Perhaps they are merely imitating something that no longer exists.

Explaining rarity is an art, plain and simple. Sometimes you can’t escape the questions of casual observers unless you retell the story of the rare Himalayan dung beetle that once thrived far and wide on the majestic droppings of the woolly mammoth but that now, like a Russian prince in exile, gets along on the meagre manure of the yak. The more I think about it, the more it seems to me it was a great mistake to replace “natural history” with the uninspired term “biology.”

But back to the satellite man.

It was the children who christened him. A journalist. A radio announcer of that heroic sort who, early every Saturday morning, year-round, tries to create broadcast entertainment by sticking a microphone under the nose of someone who
sees
something—a bird or something. “Look there! A flock of widgeons!” What can you say? No one yet has tried to broadcast ballet on the radio, but is this any better? Oddly enough, it often seems to work—more or less—at least to judge by listener polls, but of course refreshing the repertoire is a constant challenge. The bird-watching shelter these people have not visited does not exist. Again and again they stand in these places in the morning mist and chat inanely about the birds they saw last year. They’re clearly desperate. So desperate that this summer they’ve hit on the sick idea of doing some hoverfly radio.

“My, my, look here, we’ve actually found a little hoverfly. Oops, there it went.”

He arrived the evening before to set up his satellite dish on the lawn, a big parabola, because the whole spectacle was to be broadcast live. But the first thing he did was present me with a small gift, which was droning dully inside the little yellow knit sock they pull over the microphone to cut off the rustling of the wind.

“It was the only thing handy to catch it in,” he said.

A fly. The satellite man had brought a living hoverfly. Instead of candy or a bottle of wine. It had been trying to escape through a closed window on the boat from the mainland, and the announcer thought it was pretty and would make a nice present. I peered cautiously into the sock and closed it up again quickly. Was it really possible?
Eristalis oestracea
. A species I had never seen. Neither before nor since. It became the only exception to my rule.

The radio programme was more run-of-the-mill, not exactly legendary, but years later you could still hear hardened islanders telling one another about the idiot who ran around on the boat trying to catch a bumblebee in a shag sock.

…

The boat to the island takes only ten minutes, but the water is very deep. Ten minutes isn’t long, but it’s enough for a conversation about essential things—land sales, infidelities, maybe a rare-bird sighting. Conversations of this kind on the boat can be very rewarding and pleasant, although the words said are banal and few. They are nevertheless full of vitality, because the journey’s duration is measured. Everyone knows how long it will last and they plan what they will say accordingly.

Nothing promotes concentration like a known limitation of time, sometimes of space as well. If you don’t know where the limit lies, then it’s chatter as usual. Like life itself. Vague and dawdling. Or like one of those conversations that arise when trains are delayed. The train suddenly stops. No one knows why. Time passes. You begin talking to the person sitting beside you, but since neither one of you knows how long the delay will last, the conversation takes no fixed shape. Only when the train starts again and you know how much time you’ve got, only then do you make real contact. Often right before one of you gets off, or both.

“When are you going home?”

That was always the first question the children asked when people came to visit. Only then were they willing to make acquaintance.

…

The genus
Eristalis
consists entirely of impostors, a good dozen species on the island, of which most look like bees. One of the most common—
Eristalis tenax—
looks so very much like a honeybee that you can seldom be really certain as it whizzes past. Its disguise is so superb that the bluff made its way right into the Bible. No other hoverfly has managed that. At least not as far as I know. The question has never had a high priority among biblical scholars.

The relevant passage is in the fourteenth chapter of the Book of Judges, in the age-old story of Samson, who eventually made the mistake of falling in love with Delilah. Though this was before that, early in the story, when he was on his way to Timnah, near the Arabian Gulf, to court a different woman entirely. As some readers may remember, he is attacked on his way by a roaring lion, which he resolutely and skilfully rips to pieces with his bare hands, for Samson was the Old Testament sort of man who had God at his back and could therefore comfortably slay a thousand Philistines before lunch. Under the circumstances, it’s hardly surprising that lions were eradicated in the Middle East. What’s remarkable is that the last of them survived into the twentieth century.

In any case, the courtship succeeded and some time later, when Samson was on his way to the wedding, he once again passed the place where he had killed his lion. Curious, he inspected the remains and found to his amazement that a swarm of bees had taken up residence in the cadaver. Without hesitating, he gulped down some of the honey and then came up with the brilliant idea of putting one over on his wedding guests with a riddle. “ ‘Let me tell you a riddle,’ Samson said to them. ‘If you can give me the answer within the seven days of the feast, I will give you thirty linen garments and thirty sets of clothes. If you can’t tell me the answer, you must give me thirty linen garments and thirty sets of clothes.’ ”

Hard to imagine what he wanted with all the clothing. Games and gambling were maybe just a way of passing the time during such a long party. In any event, the guests took the bet and asked in unison to hear it. It went like this: “Out of the eater, something to eat; out of the strong, something sweet.” And of course they couldn’t guess it. Not a glimmer.

The only way for the guests to come up with the somewhat far-fetched answer (rotting lion generates bees) was to turn to Samson’s new bride and threaten her with arson and death unless she could slyly inveigle a hint from her husband. She did, the guests solved the riddle, and the whole thing ends with the traditional orgy of violence when Samson slays thirty men (which was God’s plan from the beginning) before returning home alone, seething with wrath. The rest of the story is all vengeance in various forms until Delilah comes into the picture and everything goes straight to hell. There’s not much more to be said. The Book of Judges is like that. What’s interesting are the bees.

Those who know the Bible are said to be pretty much in agreement these days that the swarm of bees in the lion’s carcass is only an expression of the ancient superstition that honeybees could generate spontaneously from ordure and various kinds of putrefaction. This belief was not questioned until the seventeenth century, and even much later, many people were unwilling to accept the idea that these bees, crawling from the stinking stew of corruption, were nothing but so-called drone flies,
Eristalis tenax,
hoverflies disguised as bees. It was these drone flies that Samson saw. The honey is only one more in a long line of tedious later additions.

…

But in the long run, doesn’t it get monotonous? Sooner or later, I always get that question. True, the island isn’t large. And the number of hoverfly species is not unlimited. Pretty soon they’re all there in the drawers. My good friend, the foremost expert, often says that if I’m lucky and live a long time I may find as many as 240 species on the island, hardly more. And years will pass between the last finds. That’s just the way the fauna and the island are. Even now, after seven years, I find it hard to catch anything new. But monotonous? No, no. Lonely maybe.

For an entomologist, fifteen square kilometres is a whole world, a planet of its own. Not like a fairy tale you read to the kids again and again until they know it by heart. Nor like a universe or a microcosm, similes I’m not willing to accept, but like a planet, neither more nor less—but with many white patches. Even if I were to swing my net an entire summer without adding a single species to my collection, the gaps in our knowledge will still be great, if not quite immeasurable. The fact is, they keep growing, keeping pace with our knowledge. Like that morning when the world changed.

It was a perfectly ordinary day in July, and I had just seated myself in the morning sun to eat my breakfast and watch the Caspian terns fly in from the outer islands to fish in the lake. At first I noticed nothing unusual, because you always get a little thick-witted along towards high summer, but however that was I glanced out at my oregano patch, which I planted only because the oregano blossoms attract a lot of flies. Something wasn’t right, something about drone flies.

It’s important to the story to know that I had devoted a lot of time that year to the different species in the
Eristalis
family. They’re hard. Well, not
oestracea,
of course, but many of the others. Several very common species look roughly alike, and to tell them apart on pins, you have to sit at the microscope for a long time and vacillate. Sometimes it’s easier to identify them in the field, without even catching them, because at least a couple of the drone flies that look very much alike behave quite differently. They fly at different times of the day and they don’t visit the same flowers. I’d been amusing myself with these very problems, without making much progress, I have to admit, but I had learned enough to see when something didn’t make sense. The flies on the oregano looked to be some completely new species. And even stranger, they were everywhere.

I still find new species every summer, single specimens, unexpected finds, flies that have been here the whole time in such infinitesimal numbers that they’ve eluded me. I am convinced that no matter how long I continue, my collection will always include some puzzling solitaries. But this was something else. It was, to be sure, a new species—
Eristalis similis
—but the mystery was that my oregano was crawling with them. Just this first day I’m sure I saw hundreds. And they were big, like bees. The scope of the enigma was in the books, where it said that this species had been captured in Sweden only once before, on the island of Gotska Sandön, and only one specimen.

The world had definitely changed. This was an invasion.

It is at such moments that the entomologist becomes a storyteller. He is prepared to do almost anything to get someone to listen and perhaps understand. He is prepared to use any ruse or artifice to avoid being the only one who sees. He can endure solitude better than most, but not at such a moment.

Later I learned that the invasion of
Eristalis similis
had occurred on a broad front all across the country. The species had poured in from the southeast like a cloud, and considering how many I saw on the island that first day, there must have been hundreds of thousands, maybe millions, of flies involved. They do that sometimes, hoverflies—have a fit and fly away en masse. We don’t always know why, but we must assume that this behaviour has its benefits. This particular species seems to have established itself, at least here on the island, for I now see several every year. Of course they too could be migrants, but my guess is that they live here and like the place. In any case, the species that move every year do flourish, the notorious long-distance fliers in genera like
Eupeodes, Scaeva
and
Syrphus
. Their larvae live on aphids that occur very unevenly, with sudden massive numbers in some particular place, so it pays the flies to operate across large areas. If there are lots of aphids for the moment in some other part of Europe, they fly there. It is completely pointless to band them, unfortunately, and not even the Japanese have managed to build a radio transmitter of an appropriate size, but it is nevertheless possible to map the movements of the most peripatetic hoverflies by examining the grains of pollen in their coats and determining where these originated. It’s nit-picking work, but it produces results.

When the rewards of hunting for new species begin to dwindle, I’ll probably switch to solving mysteries. There are a lot of them, believe me. Certain species are primarily known for being enigmatic. And one of the biggest of these is
Doros
.

I sometimes hear rumours that the riddle has been solved, that someone has found the larvae and managed to elucidate an intricate relationship with some kind of subterranean aphid that lives in roots, but there is not yet any credible evidence. The case is complicated by the fact that
Doros profuges
is so desperately capricious in its behaviour. Despite being large and attractive and unlike any other insect, and despite its occurrence in almost every European country, we still know almost nothing about it. No one knows what it lives on or why it’s so sporadic. It just appears somewhere, a single specimen, and is then not seen again. It is uncommon everywhere. For anyone to find two in the same place is very unusual. Why?