It sounds a little unbelievable at first. A caterpillar turns into what is basically a biological soup inside a chrysalis, then re-emerges as a butterfly or moth with wings, new senses, and a completely different lifestyle. So you’d assume everything from the caterpillar days gets wiped clean, right? No memories, no lessons learned, no lingering fears. But science seems to be quietly disagreeing with that idea. Researchers have found that butterflies and moths might actually remember things they learned as caterpillars. Not in a “flashback” way, obviously, but in subtle behavioural choices. It’s a bit like moving to a new city, changing your wardrobe, and still remembering which foods made you sick years ago. The more scientists look at insect brains, the more surprising they seem.
How scientists tested memory in caterpillars
Scientists didn’t just sit around wondering if caterpillars have memories; they tested it. In one experiment study published in PLOS titled “Retention of Memory through Metamorphosis: Can a Moth Remember What It Learned As a Caterpillar?”, caterpillars were exposed to a strong-smelling chemical, the same kind used in nail polish remover. Every time they smelled it, they got a mild electric shock. Nothing cruel, just unpleasant enough to make an impression. Pretty quickly, most of the caterpillars learned to avoid that smell. That part wasn’t shocking. What was surprising came later. After these caterpillars transformed into adult moths, researchers tested them again. The moths still avoided the smell. Somehow, the lesson stuck. It seems the caterpillar brain didn’t completely reset after all.
What was believed before the experiment
For a long time, people believed that metamorphosis erased everything. The idea was that the caterpillar’s body, including its brain, broke down entirely and was reassembled from scratch. Scientists even joked about “caterpillar soup.” But this study suggests that at least some brain structures survive the transformation. Certain neurons appear to stay intact, carrying information across stages of life. That’s wild when you think about it. It’s like renovating a house so completely that it looks brand new, yet still keeping the old wiring hidden inside the walls. Memory, it turns out, might be more resilient than we thought.
Why those memories might matter
This discovery isn’t just a fun fact for bug lovers. It might help explain real-world butterfly behaviour. For example, female butterflies are incredibly picky about where they lay their eggs. They often choose the same types of plants they ate as caterpillars. That could be memory at work. If a plant was safe and nutritious before, it makes sense to trust it again. There’s still debate about how strong these memories are, but the possibility is fascinating. It also hints at how brains recover after damage in humans. If insect brains can preserve memories through total body reorganisation, that says something hopeful about neural flexibility.
Why caterpillar memories could influence adult butterfly behaviour
Insect brains don’t just shrink or grow; they reorganise intelligently. Even with only a fraction of our neurons, they can store experiences for weeks or months. In the case of moths, memories from a crawling, leaf-chewing life can influence a flying, nectar-seeking one. That’s a massive lifestyle change by any standard. It’s kind of like remembering how to ride a bike even after switching careers, cities, and identities. Not bad for a creature with a brain smaller than a grain of rice.So the next time you see a caterpillar inching along a leaf, remember this: it might be learning something it will carry for life.