There are few children’s books more beloved than Eric Carle’s The Very Hungry Caterpillar. Since its original publication in 1969, it has sold upwards of 50 million copies. Carle’s combination of beautifully constructed collages, elegantly simple prose, and cleverly holey pages has formed a magical part of an unfathomable number of childhoods.
Yet when you consider exactly what the caterpillar eats, it’s hard not to think that, rather than ending the story as a beautiful butterfly, the titular insect would meet an untimely end by rupturing open and dying horribly, his little caterpillar guts spilling from his torn, distended flesh.
Insects and Sensibility
The caterpillar eats a lot. It’s an apple on Monday, two pears on Tuesday, three plums on Wednesday, four strawberries on Thursday, and five oranges on Friday. Then along comes the debauchery of Saturday, a caterpillar Woodstock of overindulgence, in which our cute little pal eats a piece of chocolate cake, an ice cream, a pickle, a hunk of cheese, a slice of salami, a lollipop, a piece of cherry pie, a sausage, a cupcake, and a slice of watermelon. Then it spins a cocoon, chills inside for two weeks, and emerges as a beautiful butterfly.
The truth is, real caterpillars are slightly more sensible eaters. As Jesse Varga, lab manager of The Caterpillar Lab—a New Hampshire-based nonprofit organization aimed at educating the public about caterpillars—explains, most caterpillar species only eat leaves, and many only eat one specific type of leaf due to a shared evolutionary history with that particular plant.
"Some do eat fruit and bore into plants," Varga tells Mental Floss, "although most fruit-boring caterpillars live their whole larval stage in one fruit, and only get through a fraction of it. And no caterpillar really eats, or could even eat, any of the Saturday foods."
(What we call a caterpillar is the larval stage of a butterfly or moth. Despite having lots of legs, and six-leggedness being a key tenet of insectdom, a caterpillar is an insect.)
The Very Hungry Caterpillar's constant increase in food intake, however, is one of the more realistic elements of the book, although in real life it is actually more dramatic—less of a linear increase and more of an exponential one.
"Caterpillars go through five growth stages, or instars," Varga says. "They shed their skin each time, replacing it with a bigger skin. Cecropia caterpillars hatch out of eggs the size of a grain of quinoa. When they hatch, they are about half a centimeter long. The second instar is about 1.5 centimeters long, the third about 2.5 centimeters, the fourth around 6 centimeters, and as a fifth instar they can be 12 centimeters long. A first instar cecropia takes several days to eat a small cherry leaf, but a big fifth instar might eat 15 leaves in one day."
Butterflies and Lies
So what about Sunday, when Carle’s caterpillar chills out with a single leaf due to a stomachache? Nope. The bigger a caterpillar is, the more it eats. Plus, while different species spend different amounts of time in each development stage—weather and time of year also play a part in how long each stage lasts—one week from egg to pupation size isn’t in the cards for any caterpillar. Not even a Very Hungry one.
Finally (and none of this takes away from the beauty of Carle’s masterpiece) butterflies don’t make cocoons. All lepidoptera enter a pupation stage where they are immobile. While some moths spin cocoons to protect themselves before pupating, and others opt to do it underground or within shelters made of leaves, butterflies do not. They have evolved so that their pupa skin looks like a leaf or a twig, allowing them to hide in plain sight, cocoon-less.
The Very Hungry Caterpillar is a great book—and Carle is a wonderful man who has inspired millions to share his love of nature (and has a really interesting spider named after him). But the salami-chomping, ice cream-loving, sausage-toting caterpillar? Not a thing.