Goo has memories of electric shocks
When I was ten or eleven, living in the small seaside town of Minehead in south-west England, I made friends with a girl who lived in my cul-de-sac. I don’t remember her name. Our families both lived in one of those stuck together rows of houses—similar to what I live in these days.
My mum hated those houses, but my auntie described them as like being hugged on both sides (which made my introverted mother dislike them all the more). I think they are called terraced houses in the UK; here in NZ we call them townhouses.
I liked living in a terraced house. I liked knowing everyone around me had the same house and the same layout and the same size backyard. It felt equalising, although I wouldn’t have been able to express that back then. I felt normal, for the first time in my life. Kids would play at the end of the street—it wasn’t quite a cul-de-sac, but close enough. Quiet enough to play safely, with plenty of warning of any slow-moving cars. That’s how I met this girl.
But this isn’t about houses (for once). It’s about caterpillars.
The girl and I agreed we’d meet the next morning to walk to school. It was a roughly half-hour walk to the middle school, so it was nice to have company, and I no doubt had visions of a new neighbourhood bestie.
We had barely made it halfway along our walk when she stopped and pointed out a caterpillar on a stone wall. I paused to admire it, as you do when you’re a child and a new friend points out a bug. Except this new friend pulled a box of matches out of her pocket and proceeded to burn the caterpillar. To death. While laughing.
I was immediately horrified and told her it was an awful thing to do. She was unrepentant and said, “it’s just a caterpillar”. Which is true, it was just a caterpillar… minding its own business, doing no harm, suddenly being scorched alive.
As a child I assumed that a caterpillar goes into its chrysalis or cocoon, hangs there sprouting wings, and eventually hatches. The same caterpillar body, now magically with wings! I was never interested enough in entomology to learn more about it and was content with this assumption well into adulthood.
Turns out the truth is, well—rather repulsive. But also kinda cool. When a caterpillar goes into its chrysalis or cocoon, it turns into goo. It liquefies. But listen, it’s even worse than it sounds. Because what the caterpillar is doing is releasing digestive enzymes that consume itself. If you open a chrysalis at the right time (wrong time?) liquid will ooze out.
Gross. Let’s move on from the self-digested soup and get to the magic, which starts with tiny little cell groups called imaginal discs. I don’t know what they are either, but it’s a key part of the process. During the transformation from caterpillar to butterfly, these imaginal discs rearrange themselves to produce this new creature. It didn’t just sprout wings from its caterpillar body, it grew a whole new body out of the liquid remains of its first body.
Scientists have wondered if adult moths and butterflies can remember experiences they had as larvae—caterpillars—despite being liquidised through their metamorphoses. Does imaginal disc soup remember its previous life after all its ingredients are rearranged?
It’s pretty hard to know what insects might remember, but in a study published in 2008, a group of scientists set out to figure out if moths could remember something from when they were caterpillars.
They used a Y-shaped pipe for tobacco hornworm caterpillars to crawl through. One chamber had your bog-standard air, and the other chamber smelled like ethyl acetate, a chemical often used in nail polish remover. So it had a strong smell, but it was neutral—not something that was naturally off-putting or harmful to the caterpillars. When a caterpillar went into the chamber with the ethyl acetate, they were administered a mild electric shock.
Seventy-eight percent of the caterpillars that were shocked directly after exposure avoided the chamber with the chemical in it during subsequent tests while they were still caterpillars, showing they had developed an aversion to the smell.
About a month later, after the caterpillars had transformed into moths, seventy-seven percent of them also avoided the ethyl acetate smell, indicating that they had a memory of the electric shock they had experienced as larvae.
Somehow, despite their central nervous systems dissolving into sludge, memories remained.
Metamorphosis sounds pretty traumatising, and we all know a million clichéd things have been written about our own processes of metamorphosis, our own growing pains, the way many of us go through some kind of trauma before we can emerge on the other side a beautiful butterfly.
I don’t like the metaphor, though. Trauma doesn’t feel beautifying to me. It feels like the sludge. So I’m not going to add to those million oversimplified toxic-positivity things by suggesting we also dissolve and are reborn into something joyous. Sometimes we simply dissolve.
But I am interested in the way memory holds. The way we can be triggered by a smell, like the ethyl acetate. Like how I had hyperemesis gravidarum when I was pregnant, and spent many weeks in hospital, vomiting round the clock. My son has just turned fourteen, and to this day when I have to go to the hospital and I wash my hands, the smell of the soap brings those endless weeks of nausea back. I once wanted four children, but I stopped at one. I couldn’t get past the memories of that terrible illness, even though I knew there’d be a beautiful butterfly baby on the other side.
The things we go through are never truly left behind.
I am no saviour of bugs. I’m not one of those people who hold large creepy crawlies for funsies. I have squashed plenty in my time; insects that have frightened me when they have crawled on me unexpectedly, or whitetail spiders lurking in a corner of my house. But I try to relocate them when they aren’t welcome rather than killing them. I can’t imagine going out of my way to approach something—anything—in order to hurt it.
When it became clear that the girl I tried to make friends with thought nothing of her unnecessary cruelty towards the caterpillar, I crossed to the other side of the road and refused to speak to her ever again. I don’t remember her name, but nearly twenty years later, I remember the curling sound of that tiny torture. If the caterpillar had lived, it would remember the smell of the flame.
That's a fantastic piece, Charlotte. A brilliant blend of science and personal.