From Bug Soup to Butterfly

From Bug Soup to Butterfly

March 20, 2020

The start of spring is all about baby animals. So our fan Audrey C. asked, how does a caterpillar turn into a butterfly? Well, the change from caterpillar to butterfly is kind of gross, but also really amazing. First, the caterpillar eats nonstop, and grows really fast for about 2 weeks. The bug ends up weighing 200 times as much by the end of it! Then it attaches itself to a tree branch and sheds its skin, under which there’s a hard skin called a “chrysalis.” Over 2 more weeks, most of the caterpillar’s body turns into goop, and re-forms itself into a butterfly. Finally the butterfly crawls out and pops open its wings. After 4 weeks of sitting with nothing to do, that butterfly must be excited to fly.

Wee ones: Like all insects, a butterfly has 6 legs. Is that more or fewer legs than you have?

Little kids: If the caterpillar eats for 2 weeks, how many days is that?  Bonus: If that all starts on a Monday, what’s the 5th day the caterpillar pigs out?

Big kids: If you started eating nonstop today (March 20), what’s the date of your 14th day of eating? (Reminder if needed: March has 31 days.)  Bonus: What if you weighed 200 times as much after that as you do now? What would you weigh? (Hint if needed: Multiplying by 200 is the same as multiplying by 2, then by 100.)

The sky’s the limit: If the whole caterpillar “metamorphosis” (growth and chrysalis) takes exactly 4 weeks, and a caterpillar partway through that has 6 times as much time left as it’s already done, how many days of metamorphosis has the little guy done?




Wee ones: The butterfly has more legs!

Little kids: 14 days.  Bonus: That Friday.

Big kids: April 2. March 21 is the 2nd day, so March 31 is the 12th day, then we count forward 2 more.  Bonus: Different for everyone…multiply your weight in pounds by 200.

The sky’s the limit: 4 days down, 24 days to go. Whatever part the caterpillar has lived already, it has 6 parts left of the same size, so there are 7 of those parts total…and 1/7 of 28 is 4 days.

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About the Author

Laura Overdeck

Laura Overdeck

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.

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