The Colours You Cannot See
there are patterns on flowers that your eyes have no part for, and they are really there — read-aloud science for four to eight, with every source kept on the page where the grown-up can find it
Here is a flower. It is yellow.
That is what you see. Yellow petals, all the way round, and a middle.
You are not wrong. It is yellow.
But that is not all of it.
This zine follows one settled thing: ultraviolet floral patterns and bee colour vision, and the correction that the popular version of it usually drops.
Large type is for the child. These boxes hold the figures, the papers and the limits. You should not have to leave the page to answer “is that really true?”
A bee lands on it and sees a target
On the very same flower, a bee sees a dark ring in the middle and bright petals around it.
Like a bullseye. Like a landing pad with an arrow painted on it saying here, this way, the middle.
The pattern is really on the flower. It is really there right now.
You are looking straight at it and your eyes do not have the part that picks it up.
Lunau, Camargo and Ren (Plant Biology, 2025) describe the “UV bull's eye” as “a UV-absorbing centre of a UV-reflecting flower,” functioning as a floral guide directing pollinators toward a reward.
The pattern is made of ultraviolet light being absorbed in the middle and bounced off at the edges. Human retinas have no receptor tuned there, and our lenses filter much of it out before it would arrive anyway.
How do we know the bee is really seeing a colour?
This is a good question and somebody asked it a very long time ago.
Maybe the bee is not seeing colour at all. Maybe it is just going to whatever is brightest.
So in 1914 a man called Karl von Frisch did this.
First he taught bees to go to a blue card, by putting sugar water on it.
Then he took the sugar water away, and he put the blue card out with a whole row of grey cards beside it — pale grey, middle grey, dark grey, every brightness he could make.
If the bees were only picking the brightest thing, one of those greys would have fooled them.
The bees went to the blue.
This is worth dwelling on with a child, because it is a control, and it is one of the cleanest ever designed. The greys are there to rule out the alternative explanation. Without them the experiment proves nothing; with them it proves the thing.
Von Frisch (1914) trained bees to a coloured card with a sucrose reward, then in unrewarded tests presented that card together with grey cards of differing intensities. He later established that bees are trichromats, with three photoreceptor types contributing to colour vision.
“How would we know if we were wrong?” is the whole of science in one sentence, and a six-year-old can hold it.
The bee is not seeing more than you
Here is where the story usually goes wrong, and the true version is better.
People say bees see extra colours, like they got everything you have and then some more on top.
That is not it.
A bee cannot see red.
Hold up something red. A bee is not seeing a beautiful extra red plus ultraviolet. It is not getting the red at all.
This is the correction the zine is built on, and it comes from the review itself. Lunau, Camargo and Ren state that “ultraviolet is merely one component of colour vision” for bees — not a separate discrete signal bolted onto a human-like system — and that “bees are sensitive to UV light, humans are not, whereas humans are more sensitive to red light compared to bees.”
The window is shifted, not widened. Writing it the popular way turns a difference into a ranking, which is exactly the move this collection exists to refuse.
You each get a different stretch
Imagine a very long ribbon of light, going on past both ends of what anybody can see.
You get a piece of it. The bee gets a piece of it.
The two pieces overlap in the middle — you both get blue, you both get green.
Then yours keeps going one way, into red. And the bee's keeps going the other way, into ultraviolet.
Neither piece is bigger. They are just in different places.
Human vision runs roughly 390–750 nm; bee vision runs roughly 300–650 nm, with photoreceptor sensitivity peaks in the ultraviolet, blue and green. Both are about the same width. Both sit in different places on the same continuous spectrum.
These figures are widely reported and we have not read the primary measurement papers for the range endpoints; they are given as approximate, and the argument does not depend on the exact numbers — only on the overlap and the two different tails.
And the ribbon goes on past both of you
Past your end there is more. Past the bee's end there is more.
Heat that you can feel on your face but never see. Radio going straight through the room right now, through the walls, through you.
Nobody has eyes for all of it. Not you, not the bee, not anybody.
Everyone is looking at a piece.
Radio, microwave, infrared, visible light, ultraviolet, X-rays and gamma rays are one continuous electromagnetic spectrum, not different substances. This zine states that and stops.
Shared Signal owns that argument here and makes it properly; repeating it would be this piece borrowing an authority it has not earned. What belongs to this zine is narrower and is on the next spread.
The flower is not hiding anything from you
It is not being sneaky. It is not keeping a secret.
The pattern is out in the open, in the middle of a sunny day, on the front of the flower.
It was simply not made for your eyes. It was made for whoever can use it — and what the flower wants is a bee, because a bee will carry its pollen to the next flower.
A thing can be perfectly obvious and still not be for you.
Careful language here on purpose: the flower is not trying anything. Floral guides are the product of selection on pollination success, not intention, and “what the flower wants” is a shorthand a four-year-old can hold and an adult should be able to unpack.
The claim that these patterns actually direct pollinator behaviour is testable and tested — and the honest summary is that it is well supported for a number of species and not a universal law of all flowers.
Real things can be there when you cannot find them
You cannot see the pattern on the flower. It is still on the flower.
Not seeing a thing is not the same as the thing not being there.
And the one who can see it is not making it up.
So if somebody tells you they can hear something, or feel something, or see something that you cannot — the flower has already shown you how that works.
You do not have to be able to find it to believe them.
We love you down to your star stuff.
That is the only step this zine takes from bees toward people, and it is deliberately the modest one. It does not claim that human sensory differences are like bee ultraviolet vision, or that anybody has extra senses. It claims something much smaller and much harder to argue with: that a real signal can be present and undetectable to a particular observer, and that this is unremarkable.
For a child who is regularly told that a sound is not that loud or a light is not that bright, the flower is a better argument than reassurance, because it is not about them.
You can go and look
You will never see ultraviolet with your own eyes. That part is permanent.
But people built cameras that can, and there are photographs of flowers taken that way — the same flower, side by side, in our light and in the bee's.
That is what people do when they cannot see something. They build a way to look anyway.
The bee did not need a camera. We did. Neither of us was wrong.
UV floral photography — a UV-pass filter and a sensor without the usual UV-blocking layer — is how most published bull's-eye images are made, and searching for it is a good next step with a child who wants more.
A caution worth having ready: a UV photograph is not a picture of what a bee sees. The bee's three receptor types, its brain, and the false colours a photographer assigns are all in the way. It shows that the pattern exists; it does not show anyone the bee's experience, and no image can.
Not:
The pattern is on the flower whether or not you can find it — and the one who can find it is not seeing more than you. They are seeing a different stretch of the same ribbon.
What has somebody in your house reported that you could not detect — and what did you do with that?
Where do you say “more” when the honest word is “different”?
What are the grey cards in an argument you are currently having — the thing that would show you were wrong?
Which room in your life was built for a receiver that is not the one using it?
Sources
The bull's eye, and the correction this zine is built on. Klaus Lunau, Maria Gabriela Gutierrez Camargo & Zong-Xin Ren, “Bees, flowers and UV,” Plant Biology 27(6), 948–961 (2025), doi:10.1111/plb.70050 — open access. Source of the UV bull's eye as “a UV-absorbing centre of a UV-reflecting flower” acting as a floral guide (spread three), and of the sentences spreads five and eleven turn on: that ultraviolet is “merely one component of colour vision” rather than a separate discrete signal, and that “bees are sensitive to UV light, humans are not, whereas humans are more sensitive to red light compared to bees.”
The grey cards. Karl von Frisch (1914) established bee colour vision by training bees to a coloured card with a sucrose reward and then, in unrewarded tests, presenting that card together with grey cards of differing intensities — the control that rules out a response to brightness. He went on to show bees must be trichromats. Randolf Menzel's work from 1967 onward established how quickly bees learn colours. We have not read von Frisch's 1914 paper; the design and the result are taken from the review literature that recounts them, and spread four states the experiment rather than quoting him.
The two ranges on spread six — roughly 390–750 nm for humans and roughly 300–650 nm for bees, with bee photoreceptor peaks in the ultraviolet, blue and green — are widely reported figures that we have not traced to the primary measurement papers. They are given as approximate on the page. Nothing in the argument depends on the exact endpoints, only on the overlap and on the two tails pointing in opposite directions, and that much is stated directly by the review above.
What we would not print
The sentence this zine exists to avoid is “bees see more colours than we do.” It is in almost every popular account, it is the version we arrived with, and it is a ranking wearing a fact's clothes. The true version is better and harder to sell: two animals get comparably sized windows onto the same continuous spectrum, sitting in different places, and each is blind to what the other has. That is the whole zine, and it would have been very easy to write the exciting wrong one instead.
And we would not let a photograph overreach. UV floral images are the most persuasive thing in this subject and they do not show anyone what a bee sees — the receptor set, the brain and the photographer's arbitrary false colours are all in between. Spread ten says so on its own face, because a picture that impressive will otherwise make the claim by itself.
What this deliberately does not re-argue
Shared Signal owns the one-spectrum argument — that radio, infrared, visible light and the rest are a single electromagnetic field at different frequencies rather than different substances. Spread seven states it in one breath and hands it back. No. 91 and No. 93 are this zine's read-aloud siblings: pace, conditions, and now perception. All three carry the same two-layer format and the same sourcing standard, because “for kids” is exactly the shelf where a verify-everything standard quietly lapses.
A rhyme, not a proof. We are not claiming a person is like a bee. We are pointing at a signal that is measurably present, plainly visible to one animal and permanently invisible to another — and noticing how ordinary it turns out to be for something real to be undetectable to a particular pair of eyes.