Larva Locomotion
How Are Larvae Adapted to Their Environment?

Larva Locomotion
Clip #1

(Viewing Tips)

Larva Locomotion
Clip #2

Before You Watch

It's a good thing monarchs migrate by flying instead of walking! These video clips show how monarch larvae walk, in normal speed and in slow motion.

  • Describe in writing how you think a caterpillar walks, based on your memory (or your imagination).
  • Think about how people walk and write a very careful, step-by-step description. (Have a volunteer walk in slow motion so you can visualize all the tiny changes in the muscles and joints. And/or, watch this video clip of a person walking in slow motion.)
  • For homework tonight, watch a dog walk. How does it keep track of all four legs? Do its front legs jump ahead and the back legs follow? Wouldn't it be confusing to walk with four legs? Get down on all fours and try it yourself. How does your gait compare to a dog's?
Another Step: Insect Anatomy

You'll need some information and new vocabulary to describe what you're about to see: All insects have six legs. That includes monarch butterflies, even in the caterpillar stage. The pictures below show one side of the caterpillar. If you count, you might think you're seeing 8 pairs of legs. But the leg-like structures you see in the rear are not actually legs. They are called "prolegs." A proleg is an appendage that looks like a leg, and acts like a leg, but is not a true leg (embryologically speaking).

How are the monarch's prolegs different from its true legs?

True Legs
  1. located on the monarch's thorax
  2. segmented, with joints
  3. present in adult insect
  1. located on the abdomen
  2. not segmented, no joints, fleshy & shaped like a cylinder
  3. disappear in the adult butterfly
Watch the Clips

How Do Larvae Walk?
Now that you've watched carefully, describe how a monarch caterpillar walks:

  • Which of the monarch's legs or prolegs does it move first? Were you surprised?
  • How are the legs and prolegs used differently? Write a step-by-step description of larva locomotion.
  • Describe the challenge the monarch faces when walking on a leaf.
  • How is the caterpillar’s method of walking helpful for balance?
  • How does the caterpillar's body change as it walks?
  • If the prolegs could talk, what do you think they would say to each other?
  • Generate research questions while you watch. (For example: What is on the ends of the prolegs? Are they sticky? How can a caterpillar walk upside down on the bottom of a leaf without falling?)
  • Watch these video clips of a pony, a person and a pigeon walking. Compare and contrast larva locomotion to that of other animals. (Does a caterpillar slither like a snake? Crawl like a turtle? Hop like a bird?) Use similies to enhance your description.
  • Did You Know? After watching caterpillar locomotion engineers have designed heavy construction equipment, needed for driving on difficult terrain. Can you find other things that people have designed based on examples in nature? (See PARC'S Modular Robotics for some fun examples.)
Pulling it Together: Adaptions to the Environment

How Are Larvae Adapted to their Environment?

  • Where do monarch larvae spend their time?
  • What special needs do they have?
  • What are the characteristics of a milkweed plant? Look closely. Use a magnifying lens for an even closer inspection. What new things do you see? Can you find ways that the monarch's feet are adapted to those characteristics?
  • Look at the clip again. See if you find more ways that monarch larvae are adapted to their environment.

National Science Education Standards

Science as Inquiry
Ask a question about objects, organisms, events. (K-4)

Identify questions that can be answered through scientific investigations. (5-8)

Use data to conduct a reasonable explanation. (K-4)

Life Science
Each plant or animal has different structures that serve different functions in growth, survival, reproduction. (K-4)