Cosmo: Hey, Dr. Universe
Dr. Universe: Hey, Cosmo
Cosmo: Why don’t ladybugs play hide and seek?
Dr. Universe: I have no idea.
Cosmo: Because they’re always spotted!
Dr. Universe: Hey, friends. I’m Dr. Universe
Cosmo: And I’m Cosmo.
Dr. Universe: And if you’re anything like us, you’ve got lots of big questions about our world. Today we’re talking about a question sent in by a kid just like you.
Cosmo: Rachel wants to know: What is the life cycle of a ladybug?
Dr. Universe: The ladybug life cycle includes complete metamorphosis. That means they undergo big body changes to become adults.
Cosmo: Like butterflies do when they go into a cocoon as a squirmy caterpillar and change into an adult with fluttery wings.
Dr. Universe: Exactly. Insects that do that are holometabolous. They have four life stages: egg, larva, pupa, and adult.
Cosmo: I’ve seen ladybug eggs under leaves! They’re yellow or orange. They look like fat grains of rice.
Dr. Universe: After a few days, those eggs hatch.
A spiny larva comes out. It looks like a hungry little alligator. Its job is to eat and grow.
First, it chows down on extra eggs its mother left behind. A particularly peckish larva might eat its siblings—especially the small or slow ones.
Cosmo: Talk about sibling rivalry!
Dr. Universe: Then it starts snacking on nearby soft-bodied insects like aphids.
As it eats and grows, its tough outer skin gets too tight. That skin is called the cuticle. The larva pops it open
and climbs out. It has a new, bigger cuticle ready to expand and harden to fit its body.
The larva will molt like this a few times.
Cosmo: Eww. So, they just have old skins lying around?
Dr. Universe: Not for long. They usually eat that old skin. It’s free food.
Cosmo: NOOOOO.
Dr. Universe: After a few weeks of eating and growing and molting—
Cosmo: And eating old skin—
Dr. Universe: That ladybug larva is ready to transform into an adult. It sheds its cuticle one last time. But this time it stays inside. That’s now a pupal case.
The pupal case is hard. It sticks firmly to a leaf or other surface. Inside, the larva’s body breaks down. It reorganizes into an adult body.
After about a week, an adult ladybug comes out. It has soft, fluttery wings tucked under a pair of hard wing covers called elytra. Just like all beetles do.
Cosmo: The elytra are the orangey red part with black spots.
Dr. Universe: Exactly. Although ladybugs come in different colors and patterns.
Cosmo: So…they’re not always spotted in hide and seek?
Dr. Universe: Probably not. Most insects go through a big change like ladybugs do. But some only do partial metamorphosis. They’re called hemimetabolous.
They have three life stages: egg, nymph, and adult.
The immature nymphs look a lot like the adults. They’re just missing wings and working reproductive parts. They’ll get those at their final molt.
Cosmo: Wing upgrade!
Dr. Universe: The least common life cycle has no metamorphosis at all. They’re called ametabolous. The juveniles look exactly like the adult, just smaller. They never get wings.
Cosmo: Bummer.
Dr. Universe: Ametabolous insects are so well-adapted that they haven’t changed much for hundreds of millions of years. The ancestors of all insects were like that.
Complete metamorphosis—like ladybugs do—is the newest insect life cycle.
Cosmo: Why would some insects change how they change?
Dr. Universe: It’s possible metamorphosis evolved so the juveniles and adults don’t compete. Or maybe it happened that way to make better wings. But it’s still a mystery. It’s wild that so many insects break down and reorganize their bodies just to grow up.
Cosmo: You really can’t beetle an awesome adaptation like that.
Dr. Universe: That’s all for this episode, friends.
Cosmo: Big thanks to Rich Zack, an insect scientist at Washington State University.
Dr. Universe: As always, if you’ve got a science question for me, you can submit it at askdruniverse.wsu.edu. That’s A S K D R U N I V E R S E dot W S U dot E D U.
