Description
Two damselflies on a stem at Oaks Bottom, locked into the shape that everybody who watches them eventually photographs: the heart. Entomologists call it the wheel. It is one of the strangest arrangements in the insect world, and the reason for it is stranger still.
Start with the mechanics. The male is on the left. The tip of his abdomen carries a pair of claspers, and he has used them to take hold of the female directly behind her head — that is the connection at the right of the frame. She has then curled her own abdomen forward and underneath him, reaching up toward a point just behind his thorax.
Which raises an obvious question. Why is she reaching for the front of him?
Because a male damselfly has two sets of genitalia, in two different places. Sperm is produced at the far end of the abdomen, as you would expect. But before mating he loops his own abdomen forward and transfers it to a secondary organ tucked under the second segment, up near his chest. That is what she is reaching for. No other group of insects on earth does this, and nobody is entirely sure how the arrangement first arose.
The heart shape is not romance. It is plumbing.
And now the part that made damselflies famous in biology. In 1979 a researcher named Jonathan Waage looked closely at that secondary organ and found that it is not simply a delivery mechanism. It is fitted with backward-facing hooks and bristles, and its first function is to remove the sperm of whichever male came before — scooping and scraping the female’s storage organ clean before depositing his own.
It was the first clear demonstration in any animal that competition between males continues after mating, inside the female, and it changed how biologists thought about sexual selection. All of it worked out from an insect on a reed.
It also explains something you will see all summer if you look. After mating, the pair often stays joined — the male still gripping her neck — and flies about in tandem while she lays her eggs. That is not affection either. He is standing guard over his investment, physically preventing the next male from undoing his work.
One small note on these two. Both are strikingly blue, where in most of our species the female is duller. She may be one of the male-colored forms — the andromorphs described elsewhere in this collection — which is a reminder that the tidy rules always come with exceptions attached.
This is a high-resolution digital download of the photograph, made at Oaks Bottom Wildlife Refuge in Portland, Oregon — yours to print for your home or office, set as a wallpaper, or simply keep. The wide crop suits a horizontal space, and it is the most graphic shape in the whole collection.
What you’ll receive: a high-resolution JPEG, approximately 5504 × 3072 pixels in a wide crop — sharp enough to print at full photo quality up to about 18 × 10 inches at 300 DPI, and considerably larger for wall display. Delivered as an instant download the moment your order is complete.
License: Personal use only. Print it for your own home, use it as a wallpaper or screen background, enjoy it yourself. Not licensed for commercial use, resale, redistribution, or AI training. © Jonathan Swanson / JonSwan Productions. All rights reserved.