Random Butterfly Generator

What the butterfly generator does

You want a butterfly. For a drawing, a tattoo, a story, a name, a class, or because you read Danaid Eggfly on this list and had to know it was real.

This gives you one. Pull a batch and the names alone are worth it. Mourning Cloak, Question Mark, Autumn Leaf, Cracker, Blue Mormon, Great Awl.

What follows is what is actually going on inside these things. A navigation system that lives in the antennae, a migration that takes more than one lifetime to complete, and a transformation that is far stranger and more violent than the word metamorphosis lets on.

How to use it

1. Choose how many you want. One for a subject, a handful to browse the names.
2. Press Generate. A fresh set every time.
3. Press Copy to take the set with you.

The clock is in the antennae

Start with the Monarch, which is first on this list and is the one that does the impossible thing.

Every autumn, Monarchs in eastern North America fly to a handful of specific mountainsides in central Mexico. Not the same butterflies that made the trip before. Butterflies that have never been there, guided to a patch of forest their great grandparents left, across a continent, with a brain the size of a pinhead.

To do it they use the sun. Which sounds simple until you think about it for one more second, because the sun moves. It is in the east in the morning and the west by evening, so if you fly towards it you fly in a slow curve all day and end up nowhere. To use the sun as a compass you also need a clock, so you can correct for where the sun should be at this exact hour and subtract the time of day out of the reading.

People assumed for years that the clock was in the brain, because where else would a clock be.

In 2009 Steven Reppert's group at UMass found it. The clock is not in the brain. It is in the antennae.

They proved it in a way that is almost too neat. They took migrating Monarchs and painted the antennae. Clear paint on some, which lets light through, and black paint on others, which blocks it. The butterflies with clear paint navigated fine. The ones whose antennae were painted black, cutting the light that keeps the clock running, lost their bearing and could no longer hold a course, even though their eyes and their brain were completely untouched.

The timing device that makes the whole continental journey possible is sitting in a pair of feelers on the front of its head. Cut the sun off from the antennae and the map goes with it. Nobody had guessed that, and it is on this list, first in the queue.

It takes four of them to finish the trip

Now the part that is stranger than the navigation.

No single Monarch sees the whole year. The migration is a relay, run by a team that never meets.

The butterflies that fly south to Mexico in autumn spend the winter there, clustered on the same trees in their millions. In spring they begin heading north and lay eggs in the southern United States, and then they die. Their children continue north and lay eggs and die. So do the grandchildren. It takes three, four, sometimes five short-lived generations to work back up to Canada over the summer, each one living only a few weeks, each one getting part of the way and handing the journey to offspring it will never see.

And then something switches.

The generation born at the end of summer is different. It does not breed. It does not die in a few weeks. This one lives for months, holds off on reproducing entirely, and flies the entire distance back to Mexico by itself, to the exact forests, alone, in one go.

The same species makes two completely different kinds of butterfly depending on the season it hatches into. A short-lived breeding one for the leg north, and a long-lived travelling one for the whole way home. The trigger is the shortening days and the cooling air of late summer, which tell the developing butterfly which of its two possible lives to build.

So the butterfly that arrives in Mexico has never been to Mexico, was born thousands of kilometres away, is the great grandchild of the one that left, and is a physically different animal from its own parents. It is one of the strangest life histories on earth and it belongs to the orange butterfly on a milkweed in a car park.

What actually happens inside the chrysalis

Everybody knows a caterpillar becomes a butterfly. Almost nobody knows how, and the how is not gentle.

The word metamorphosis makes it sound like a smooth reshaping, as if the caterpillar folds up and unfolds into a butterfly. That is not what happens. What happens is closer to demolition.

Inside the chrysalis the caterpillar releases enzymes that digest almost all of its own body. It dissolves itself. Not rearranges, dissolves, into a thick liquid. If you cut open a chrysalis at the wrong moment much of what pours out is essentially caterpillar soup. The animal deliberately takes itself apart down to the fluid.

What survives the flood are small clusters of cells called imaginal discs. They were there in the caterpillar all along, dormant, waiting, one for the wings, one for the eyes, one for the legs, each holding the plan for a piece of the adult. When the body dissolves, these discs feed on the soup and grow the butterfly out of the wreckage of the caterpillar.

Then the strangest finding of all. Butterflies can remember things they learned as caterpillars. Experiments have trained caterpillars to avoid a particular smell, taken them through the total dissolution of metamorphosis, and found that the adult butterfly still avoids it. Something threaded a memory through the soup. The animal that comes out is not quite a new creature and not quite the old one. It kept a thread.

So the tidy children's-book version, caterpillar sleeps, butterfly wakes, is hiding one of the most extreme things any animal does. It liquefies its entire body and rebuilds a flying creature from a handful of reserved cells, and somehow carries a fragment of the old mind across the gap. That is what is happening inside every chrysalis on every windowsill, quietly, while it looks like nothing at all.

Where these come from

The butterflies here come from a list our team put together and checked by hand. Press the button and one is drawn out of it at random.

That is the whole thing, and it runs on your own device.

The names are a poem nobody wrote on purpose

Read a batch of these out loud and something happens that does not happen with most animal lists. The names are beautiful, and they are beautiful by accident.

Mourning Cloak. Painted Lady. Question Mark. Red Admiral. Dead Leaf. Cracker. Glasswing. Sleepy Orange. Autumn Leaf. Great Awl. Blue Mormon.

Every one of those was a description before it was a name, and each one is somebody, usually a Victorian naturalist, trying to tell you what they saw. The Mourning Cloak has dark wings edged in pale yellow and looked, to whoever named it, like a cloak worn to a funeral. The Question Mark has a tiny silver curl on the underside of its wing that really does look like the punctuation mark. The Comma next to it has a comma. Somebody looked that closely.

Some are describing camouflage so good the name is a warning. Dead Leaf and Autumn Leaf and Oakleaf butterflies fold their wings and become, completely, a dry brown leaf, veins and all, down to a fake stalk. The name is not decoration. It is telling you that you will not find this butterfly, you will find a leaf, and the leaf will fly away.

The Cracker is named for sound, which is rare in a butterfly, because it makes an audible clicking crack with its wings. And the Mormon butterflies got their name in the nineteenth century because the males have several very different-looking females, and the namers reached, a bit rudely, for a religious group associated with multiple wives.

So a random pull from this list is not just species. It is a set of tiny observations, made by people bent over a specimen a hundred and fifty years ago, trying to fit an entire vivid animal into two or three words. Most scientific names are dry. These ones are a field guide written by people who could not stop themselves from being poets about it.

Questions people ask

What is the difference between a butterfly and a moth?

Less than you would hope, and the line is genuinely blurry. The usual rules of thumb are that butterflies fly by day and have clubbed antennae, thin at the base and swollen at the tip, while moths tend to fly at night with feathery or tapered ones. But there are day-flying moths and drab butterflies and plenty of exceptions, and in strict evolutionary terms butterflies are really just one flashy branch that grew out of the moths. So every butterfly is, in a sense, a moth that took up the day shift and dressed for it.

How long do they live?

Shorter than people expect and it is the whole reason the Monarch relay above is so remarkable. Many small butterflies live only a week or two as adults, some only a few days. The famous exception is exactly that overwintering Monarch generation, which lives several months precisely because it postpones breeding to make the journey. As a rule, the ones that are busy reproducing burn out fast and the ones that are travelling or overwintering last far longer.

Do butterflies only drink nectar?

Mostly, through a tongue that coils up like a party blower when not in use, but not only, and the exceptions are strange. Many will drink from mud, sweat, tears and worse to get salts they cannot get from flowers, a behaviour called puddling. Some tropical species prefer rotting fruit or dung to nectar entirely. The delicate flower-sipper is partly a myth. A fair number of them are quietly drinking from things you would rather not think about.

Which one should I use for a tattoo or design?

Look past the Monarch, which is on nearly everyone. The list is full of better, stranger choices, and the names carry meaning for free. A Mourning Cloak brings its funeral imagery with it, a Question Mark is a built-in visual pun, a Glasswing has transparent wings you can see straight through. Look the specific one up before you commit it to skin, though, because the real animal is often more striking, and occasionally less, than the name suggests.

Are butterflies in trouble?

Many are, and the Monarch is the one people know, with the overwintering colonies in Mexico much reduced from historic numbers because of habitat loss along the route and at both ends. It is a good reminder that the relay described above only works if every link survives, the northern breeding grounds, the southern forests, and the flyway between. A migration run across four generations is only as strong as its most damaged stretch.

References

1. Merlin, C., Gegear, R. J. and Reppert, S. M. (2009). Antennal circadian clocks coordinate sun compass orientation in migratory monarch butterflies. Science, 325(5948), 1700 to 1704. https://doi.org/10.1126/science.1176221
2. Reppert, S. M., Gegear, R. J. and Merlin, C. (2010). Navigational mechanisms of migrating monarch butterflies. Trends in Neurosciences, 33(9), 399 to 406. https://doi.org/10.1016/j.tins.2010.04.004
3. Blackiston, D. J., Silva Casey, E. and Weiss, M. R. (2008). Retention of memory through metamorphosis: can a moth remember what it learned as a caterpillar? PLoS ONE, 3(3), e1736. https://doi.org/10.1371/journal.pone.0001736
4. Lowe, T., Garwood, R. J., Simonsen, T. J., Bradley, R. S. and Withers, P. J. (2013). Metamorphosis revealed: time-lapse three-dimensional imaging inside a living chrysalis. Journal of the Royal Society Interface, 10(84), 20130304. https://doi.org/10.1098/rsif.2013.0304