The Truth About Butterfly Metamorphosis (It's VERY WEIRD)

↓↓↓ More info and sources below ↓↓↓

Does any other creature on Earth undergo a life transformation as dramatic as the butterfly? I think not. Unfortunately, children's books about very hungry caterpillars skip all the COOL and WEIRD and GROSS stuff that happens along the way. It's time to dig into all the mind-blowing biology behind metamorphosis!

Filmed on location at the California Academy of Sciences

0:00 We were lied to as kids
1:48 Metamorphosis is more common than you think
3:36 It starts with an egg
4:46 Eat/Poop/Grow
6:05 Busting the biggest butterfly myth of all
7:23 Time to take your skin off
8:40 Inside the "sack of magic"
11:08 Metamorphosis,… metamorphosis everywhere
11:55 Why do butterflies do this?
13:42 Sign up for our Patreon!

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[johncao]

Small correction towards the end: flies don't do the metamorphosis IN rotten meat or poo, they tend to stop eating and craw away from food to pupate (otherwise the adult will immediately drown as soon as they eclose). I worked with both fruit flies and blow flies in the past and you always find the pupae far away from the food.

[jimmytaco]

Preschool teacher: And from within the fat little caterpillar burst a writhing mass of wasp larvae that ate the caterpillar from the inside out and grew up and laid their eggs inside more caterpillars!

[Beryllahawk]

As a matter of fact, no we didn't raise any butterflies in school. HOWEVER. The school I attended for 3rd grade and 5th grade (don't ask, Midland Texas has WEIRD school district lines) had a "caterpillar problem." Every year in spring there would be absolute hordes of itty slightly fuzzy pale green caterpillars, all over the ornamental plantings but also all over the walls!! A lot of the kids were freaked out by them but I was always fascinated since I knew they weren't going to bite or sting me, and finally one day in 5th grade, I caught one of the caterpillars and very carefully brought it home with me. My mother did not flip her lid, and instead gave me a glass jar to put the creature into, and told me to go outside and pick three stems off the ornamental bushes in the apartment complex, but ONLY the ones that looked just like the bushes at the school. (At that age I already knew my mother was smart, never even questioned it, ha)
She fixed up the jar so that the caterpillar couldn't easily crawl out, and we gave it its food and it was chill! I would get it onto my finger for a few moments every day just because I could, and I'd bring home a new stem every day with more leaves. Then - the weekend. Saturday morning - and my caterpillar had vanished!!! I looked high and low (well, as "high" as a nine year old can look) and couldn't find it. Very sad. But SUNDAY morning I saw the pupa!! The caterpillar had managed to get out of the jar and made its little sack of magic on the curtain.
Few days later - and there was a moth!!! A beautiful white moth with vivid tiger-orange on the inside of the wings. And though I know now as an adult that bugs don't exactly bond with anything or anybody, it seemed to me like the moth remembered me, and it flew over and landed on my shirt and just kinda sat there like "Welp. Outside now, please."
So of course I took it outside, set it carefully on a bush, and watched it fly off to do whatever moths do. And at the school? Dozens and dozens of white-and-orange moths on Monday! So many! The grownups were all super annoyed but to me it was pure magic.
To this day I have no bloody idea what kind of moth it was though. I've never found ANY picture that looks like my moth pal.

[rickseiden]

Could you imagine if humans did this? "I'm sorry, but Johnny can't come to school today. He's locked himself in his room, and isn't coming out for the next two weeks." "That's exciting, Mr. Smith. I'm sure your whole family is very proud. Please remember that when he does emerge, he will be expected to make up the work."

[mycosys]

I feel like one factor for metamorphosis is energy - the amount of energy required in the egg to create a pupal stage vs a more complex adult. The pupal stage means the mother can expend a LOT less energy and instead make hundreds or thousands of eggs that then acquire their own energy. But im an engineer - its always energy XD

[MrLeafeater]

When I finish writing/illustrating "The Very Hungry Maggot", I'll expect you to review/endorse it. Love your work.

[OlleLindestad]

Big and important correction: moths don't spin a silk cocoon INSTEAD OF becoming a hard-skinned pupa; they do it BEFORE becoming a pupa. Cut open a moth cocoon, and there's a pupa inside it.

Also, cicadas are mentioned in the same breath as beetles, but cicadas don't have a pupal stage; they're hemimetabolous. They go straight from nymph to adult.

[arisis]

I have a fear of butterflies and am trying to reduce it gradually by exposing myself (virtually) and learning about them. This was really cool to watch :)

[ketsuekikumori]

If you keep in mind that during the chrysalis stage that hard shell on the outside was once the exoskeleton of the caterpillar before metamorphosis, it makes sense that it has protowings and such.

[kienesel]

I’m genuinely surprised the chrysalis is inside the caterpillar and they just reveal it. Somehow more disturbing.

[Tser]

My sibling worked at a neurology department in their moth lab. They used the metamorphosis of sphinx moths to study neural development!

[diyeana]

You've brought back a memory from my 5 yr old self where I squished a cocoon to see what it was all about. I buried the pulp and cried.

[littlerave]

Couple years ago I had a cabbage white in my living room and let it out. More than half a year later I found its crysalis hidden behind the door inside of my fridge, where it apparently ended up as caterpillar with the groceries. Despite the cold, it pupated and eventually hatched. I also found another one next to it, which didn't hatch yet, I could feel it bobbing around carefully shaking the crysalis. I assumed it dead, took both crysalises out and ordered some resin, colours and tools to make fake amber earrings with the crysalises inside. After a week of lying on a table in the warm living room, while I was waiting for the supplies, the 2nd one miraculously did hatch as well. I guess the cool environment inside the fridge basically told it to lay dormant and wait for spring before hatching, which then it did. I was amazed.

[LeoAngora]

It seems to me that caterpillars are just a second stage of embryonic development, but external and more autonomous. Since the egg does not have enough nutrients, they must eat to continue their development. Once they secure enough food, the final transformation is done.

[TheMunchkinita]

The butterfly wings are kinda like our 2nd set of teeth.. already there but just under the surface where we can't see it.. pretty cool

[RJ_Ehlert]

Imagine parents consuming all the resources in an ecosystem and blaming the children for not having enough.

[nttk]

"This isn't kids book stuff, this is more like Silence of the Lambs." I wonder how Joe teaches his kids about the facts of life😂

[diaryofablackspinster]

I know multiple people who are scared of insects, even “pretty” and harmless ones like butterflies, despite not having bad experiences with them. I’m sure you have a video posting schedule but it would be neat to explore what draws out the natural fear of these things in a future video :)

[Manojspidey]

Why children books doesn’t have these stages explained because i think they still don’t have the age to understand that deeply.

[Brambrew]

Tldr: the caterpillar turns into a production line, only retaining basic vital organs as the rest of the body turns into liquefied mini-factories, each "factory" tasked with manufacturing a different part - legs, wings, eyes, etc. Then all the parts are assembled together and voilá, butterfly! And somehow, they can RETAIN MEMORIES after this process, remembering information from when they were a caterpillar!