Go down to the lake shore at Oaks Bottom on a summer evening, when the light has gone long and gold, and look at the tops of the grass.
There will be damselflies drifting about a foot above the stems. Not darting like dragonflies — drifting, unhurried, stopping and starting. If you move slowly they will let you get astonishingly close, and once you are close enough, they turn out to be one of the strangest animals in Oregon.
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They are both facing up the stem because that is the launch position — a damselfly takes off by letting go and dropping into flight, and pointing the wrong way costs it a wingbeat. And they are spaced out because males hold small territories along the bank, patrolling a few meters of reeds each and chasing off anything that crowds them. What looks like two insects that happened to land near each other is two neighbors who settled the boundary some time ago.
What You Are Actually Looking At
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Three quarters of a damselfly is that long thin tail, and it weighs almost nothing. It is not really a body — it is a boom. It works as a counterweight and a rudder, which is what lets something this light turn precisely and hold a hover in moving air. It also has to be long enough to curl right around and reach the front of another damselfly, for reasons we will get to.
Damselfly or Dragonfly?
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Two marks settle it, and the first is enough on its own.
The eyes. A damselfly’s sit wide apart, one on each side of the head, with a clear gap between them. A dragonfly’s are so large they meet in the middle and wrap the head like a motorcycle helmet.
The wings at rest. A damselfly folds them back along its body. A dragonfly holds them out flat, like a plane on a runway.
Also worth knowing: a damselfly is the slighter, weaker flier of the two, which is exactly why you can approach one. More on that shortly.
Five Eyes
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Each compound eye is split into two zones doing two different jobs, because the two halves of a damselfly’s world are nothing alike.
Looking up, everything is bright sky and the task is spotting a small dark speck moving across it. That wants big light-gathering facets and pigments tuned to short wavelengths — blues and ultraviolet.
Looking down, the world is cluttered green and the task is telling one thing from another. That wants finer resolution and sensitivity to longer wavelengths.
So it grew both, in one dome, with the boundary running horizontally across the middle. The color difference is the visible edge of that division. Bifocals, arrived at a very long time before we thought of them.
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Between the two big eyes sit three small ones. They are called ocelli, and they cannot see pictures at all — an ocellus is closer to a light meter than a camera.
What they do is measure brightness extremely fast, several times faster than a compound eye can process a scene. And from the air the world divides neatly into a bright half and a dark half: sky above, ground below. Three sensors in a triangle, each angled slightly differently, can therefore read which way up the insect is and how quickly that is changing. Tip to one side and one brightens while another dims.
It is an artificial horizon. The signals run almost directly to the muscles that steer the wings, bypassing the slow business of looking at anything, so the correction happens before the animal has registered the tilt. We fit the same instrument to aircraft and consider it essential.
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Each dome is built from thousands of separate lenses, all pointing slightly differently. What gets assembled from that is not a sharp picture like ours — it is a coarse mosaic with an extraordinary sensitivity to movement. It will notice a hand approaching long before it could resolve what a hand is.
The Wings
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Much of the blue and turquoise on a damselfly is structural color — not pigment, but microscopic layered structures in the cuticle that interfere with light and throw particular wavelengths back at you. There is nothing blue to scrape off. It works the way a soap bubble works, which is why it shifts as the animal turns and why it survives in museum specimens long after real pigments have faded.
Now find the small dark rectangle near the tip of each wing, on the leading edge. That is the pterostigma, and it is a lovely piece of engineering: a deliberate weight, placed out near the tip, to damp the flutter that a thin fast-beating wing is prone to. Aircraft designers solve the identical problem with mass balances on control surfaces. The damselfly got there first.
And unlike most insects, which flap by deforming the whole thorax, damselflies and dragonflies have muscles attached directly to each wing. All four can be driven independently. That is what buys the hovering, the sudden stops and the sideways drift.
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There is no pigment in those wings whatsoever. What you are seeing is thin-film interference — the soap bubble effect again, but this time in a membrane a couple of micrometers thick. Light bounces off the top surface and the bottom surface, the two reflections travel slightly different distances, and where they line up a color appears. Ten degrees of camera movement and this frame would have shown two panes of clear glass.
Notice also that the wings are held half open, which is exactly what I told you damselflies do not do. There is a family called the spreadwings that perch precisely like this, and they exist mainly to embarrass anybody who has just finished explaining the rule. Field marks are strong tendencies, not laws.
How They Hunt
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Here is the thing I only worked out by watching them, and it explains everything else about how they behave.
Dragonflies are hawkers. They take prey out of open air at speed, which is why they patrol over water like fighter aircraft. Damselflies mostly glean — drifting slowly through vegetation, picking small insects directly off leaves and stems, then carrying the catch to a perch to eat.
The slow flight is not a limitation. It is the method. You cannot pluck an aphid off a blade of grass at thirty miles an hour. And it is precisely why they are so approachable — a hawker has to keep moving, a gleaner can afford to potter.
The legs are the giveaway. Set far forward, heavily bristled, and close to useless for walking, they fold into a basket beneath the head to scoop prey out of the air and then serve as the plate it eats from. They are cutlery, not feet.
The diet is midges, small flies, aphids and mosquitoes, in quantity, all day. A pond with damselflies around it has a mosquito program that nobody had to install.
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He is not visiting that flower. Damselflies take no nectar and no pollen and have no interest at all in what a bloom is offering. He is using it as a hunting platform — a high stable perch with a clear view, to watch from and launch from.
It is a good lesson in how easy a photograph is to misread. This looks exactly like a pollinator picture. It is a picture of a predator sitting in a hide.
He and She
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Females in most of our species are markedly duller than the males — olive, bronze, dusty green rather than electric blue. People assume they are a different species and photograph them far less, which means half of every population goes largely unrecorded.
The reason is what she has to do to lay eggs. She does not scatter them. She has a blade-like ovipositor and uses it to cut slits into plant tissue, inserting eggs one at a time at or just below the waterline. That takes time, in one fixed spot, completely exposed.
And in some species she goes further: she climbs down a stem and submerges entirely, working underwater for half an hour or more, breathing from a film of air trapped against her body by fine hairs. Then she has to break back out through the surface, which at that size is genuinely dangerous physics.
Being hard to see is not modesty. It is equipment.
Although — and this complicates the tidy story — in several species some females hatch out looking like males, in the same bright blue. Biologists call them andromorphs, and the leading explanation is that it reduces harassment: males pursue anything that reads female, relentlessly enough to interfere with feeding and egg-laying, so a female that passes for male at a glance gets left alone to work.
The Wheel
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The heart shape everybody photographs. Entomologists call it the wheel, and the reason for it is not romance.
The male grips the female directly behind the head using claspers at the tip of his abdomen. She then curls her own abdomen forward and underneath him, reaching toward a point just behind his thorax. Which raises the obvious question: why is she reaching for the front of him?
Because a male damselfly has two sets of genitalia. Sperm is produced at the far end of the abdomen, as you would expect, but before mating he loops forward and transfers it to a secondary organ tucked under his second segment, up near the chest. That is what she is reaching for. No other group of insects on earth does this.
The heart shape is not sentiment. It is plumbing.
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And now the discovery that made damselflies famous in biology.
In 1979 a researcher named Jonathan Waage looked closely at that secondary organ and found it is not simply a delivery mechanism. It carries backward-facing hooks and bristles, and its first function is to remove the sperm of whichever male came before — scraping the female’s storage organ clean before depositing his own.
It was the first clear demonstration in any animal that competition between males carries on after mating, and it changed how biologists think about sexual selection. All of it worked out from an insect on a reed.
It also explains two things you will see all summer. Pairs stay locked together for a long time — minutes to well over an hour — because while he is attached, no rival can reach her. And afterwards he often keeps hold of her neck and flies about in tandem while she lays, guarding his investment. They can fly like that, as a single awkward two-headed animal, which looks like a mistake the first time you see it and is not.
Three hundred million years of sperm competition, and it still makes a perfectly good valentine. This one is free to take from the funny page, along with the rest of them, if you have somebody who deserves it.
Free to use. Please leave the watermark on.
Where They Come From
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Everything delicate about these animals is a recent development.
A damselfly spends the great majority of its life underwater, as an aquatic nymph, for months and in some species more than a year. Down there it is not delicate at all. It is an ambush predator, and it is equipped for it.
The nymph’s lower jaw is a hinged, spring-loaded arm folded under its face. When something edible comes in range that arm launches, grabs, and folds back into the mouth in a fraction of a second. It is among the fastest predatory strikes in fresh water — and if it sounds familiar, the creature in Alien was built along the same lines.
Then one day it climbs a stem into the air, splits its own back open, and hauls itself out as the animal in these photographs. Soft, pale, wings crumpled, standing on a leaf while it hardens. That stage is called teneral and it lasts hours. It is the most vulnerable the animal will ever be.
So the small green thing beaming over the edge of a leaf has just finished a year as a submerged predator and rebuilt itself into something that flies.
Where and When to Look
Where: the long grass along the lake shore at Oaks Bottom, and the vegetation at the edge of any still or slow water. They need water to breed and they rarely stray far from it.
When: late spring through late summer. Late evening is best for numbers — that is when they gather in the shoreline grass. Early morning is best for photographs, because a cool damselfly is a slow damselfly.
How: slowly. That is the whole technique. They will tolerate you at a distance that would be unthinkable with almost any bird.
And here is the thought I keep coming back to at that shoreline. Most damselflies live their entire adult lives within a few meters of the water they emerged from. An osprey I photograph on the same river will fly to Central America and back. One of those journeys gets written about. Both are complete lives. One is just easier to walk past.
🔒 Members: how these macro shots are actually made
The next section is for members — focus stacking explained properly, why stopping the aperture down does not work, the time of day that makes it possible at all, and how to approach an insect without moving it.
Quiz: Twelve Questions on Damselflies
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