Have you ever wondered how many legs caterpillars have or if caterpillar “feet” are sticky? We have! So we asked expert moth-er David Moskowitz (hand pictured) to answer our questions:

How many legs does a caterpillar have? Do they all have the same number of legs?

David: Most caterpillars, like all insects, have 3 pairs of legs (6 total legs), and these are located under the thorax near the front of the caterpillar. These are a caterpillar’s true legs. What makes them true legs is that they are segmented. But caterpillars also have something else special. They have prolegs on the abdomen. Usually there are five pairs (10 total prolegs). (Some caterpillars have fewer prolegs.)

Prolegs aren’t real legs. They are a fleshy unsegmented part of the abdomen. But they are critical for helping the caterpillar move. At the bottom of each proleg is a structure with a funny name – crotchet. Crotchets are a lot like Velcro, and by adhering to a surface help the caterpillar grasp. That attachment and muscles in the body move the prolegs like they are actual legs. 

A caterpillar glows under UV light. Image: David Moskowitz
Is it safe to pick up caterpillars? What does it feel like to hold a caterpillar? 

David: Some caterpillars are very fun and safe to handle. But others, have sharp spine or irritating hairs and can cause a strong painful and often burning reaction. So it’s best to only handle a caterpillar with someone who knows about them. Caterpillars are also very soft and squeezing them too hard or dropping them will injure them. 

Challenge questions

Now that you’ve read David’s answers to our questions about caterpillar legs, see if you can answer these challenge questions:

Can you identify the legs and prolegs in these pictures?

Are these legs or prolegs?

How did you do?

David Moskowitz, PhD, is an expert on moths and one of the co-founders of National Moth Week, a global citizen science initiative collecting data about moths around the world. David is also a Senior Vice President with EcolSciences, Inc. an environmental consulting firm in Rockaway, New Jersey. 

Moth Week 2022 is July 23-31.