Episode 313 – Saddleback Caterpillar: A Tiny Steed

“…and today we’re talking about a tiny little steed. But more on that later.”

Out here in the wild wild west of… let me check my notes… Yucatan Mexico. That’s not very West. Well, out here in the wild wild… East, you won’t get too far without your trusty saddle as well as your trusty skirt of poisonous barbs. The saddleback caterpillar is never without these two trusty tools as it slinks along its favorite leaves. Because it’s so well-equipped, it doesn’t need to hide or blend into the background like all those lily-livered, yellow-bellied coward caterpillars, some of which actually have yellow bellies. But telling others just how deadly you are is a great way to survive here in Life, Death, and Taxonomy.

Description of the Saddleback Caterpillar

During the middle and late stages of development (also called slug time), the caterpillar exhibits its distinctive lime-green coloration on the upper part of its body, which includes a dark marking at the center, enclosed in a white and black pattern that looks a little bit like a tiny saddle.

It sort of looks like someone threw a tiny green blanket over its back and placed a small reddish-brown saddle on it.

The green color of the body stands out in contrast to their dark front halves and their butts. 

The skirt of the body, towards the bottom, contains tubercles with hollow spines. 

Once the caterpillar goes through metamorphosis, it throws off its saddle, becoming a light brown and cream-colored moth.

Measure Up

Welcome to the beloved Measure Up segment. The official listener’s favorite part of the show! The part of the show when we present the animal’s size and dimension in relatable terms through a quiz that’s fun for the whole family. It’s also the part of the show that’s introduced by you when you send in audio of yourself saying, singing, or chittering the words Measure Up into ldtaxonomy at gmail dot com. We don’t have a new Measure Up intro!

Caterpillar (Alice in Wonderland) 0:43


  • 1.5 to 2.0 mm (0.06 to 0.08 in)
  • How many saddleback caterpillars go into the length of the Mongol Derby?
  • Hint: The derby features around 40 or so contestants from multiple countries, riding horses through the Mongolian Steppe. It is considered the longest horse race in the world. The race is intended to pay homage to the horse messaging system that was developed by Genghis Khan in 1224.
  • 491,040,000 caterpillars. The race is 1,000 kilometers (620 mi) long.


  • 1 mm (0.04 in)
  • How many saddleback caterpillars go into the diameter of a Clydesdale horse hoofprint?
  • Hint: Clydesdale’s are among the largest horse breeds along with the shire horse and Belgian draft horse. 
  • 500 saddleback caterpillars. Around 20 inches in diameter. 

Fast Facts about the Saddleback Caterpillar

Saddlebacks are indigenous to North America and are well-known for inhabiting tropical regions such as Yucatan, Mexico. 

However, they can also thrive in the moderately cooler conditions they might find in the eastern United States.

Adult moths fly during warm months, which can be year-round in the south or between July and August in the U.S.

They are polyphagous because they eat a wide range of plant life, but they seem to gravitate towards palm trees. 

As a caterpillar, they go through three instars and a series of molts before making their pupas. Pupas are light brown with black veins and is surrounded by silk webbing. The silk is a way to attach the pupa to whatever leaf it’s on and protects the pupa from predators.

Adult moths are brown and fuzzy. They only live around ten days, in which they must mate to start the next generation.

Major Fact: I Want My Saddleback, Saddleback, Saddleback

It’s no surprise that caterpillars are prime pickins for any animal that has bugs on the menu. After explaining to Mason what animals eat, the answer is usually grass, meat, or bugs.

Lots of things eat bugs, lizards, snakes, birds, frogs, toads, larger bugs, spiders, and even people. And a meaty, slow, defenseless grubbin like a caterpillar is a tasty appetizer.

But what if a caterpillar decided to fix one of its weaknesses? No, not a fast caterpillar (though that would be terrifying).

What if it wasn’t so defenseless?

Most caterpillars’ only defense mechanism is camouflage – to be green like the leaves they hang out on so that predators can’t spot them from a distance. The saddleback brothers take a different approach.

Firstly, they sport eye-like spots on their rumps to confuse and disorient potential predators. The predator sees them crawling one way but looking with large eyes another way and that gives it pause. Giving it time to register that these bright colors are there for a reason. Their vibrant, attention-drawing colors are like a personal challenge: “eat me and see what happens”

This is called aposematism or warning coloration and it shows predators that you don’t want to mess with them.

The reason you don’t want to mess with them is due to the bright orange hollow rigid tubes that act as spines lining the caterpillar’s flanks.

They ball up so that anything that attacks them has to get through the sharp spines first. The spines are not only sharp, but they’re also filled with a toxin secreted by a gland that will be injected into whatever manages to snap one of the spines.

If a human is stung, they usually experience pretty bad hives, headaches, conjunctivitis, difficulty breathing, gastrointestinal symptoms, asthma complications, anaphylactic shock, and hemorrhaging. These can last for days.

Saddlebacks like nice flowers and so do gardeners so these are the people most likely to get stung. The spines can fly through the air when they break and can become embedded in your skin so you need to get it out so it doesn’t cause prolonged issues.

I think I’d rather get bit by most spiders than get stung by one of these

Ending: So slug along your plant, bristle those spines, and try your best to look like a horse if you don’t want to get eaten like the saddleback caterpillar here in LDT.