Leggy Bugs—Caterpillars (Lepidopteran Larvae, which Become Butterflies and Moths)

Butterfly and moth caterpillars have fewer legs than the leggy bugs I wrote about last month (“Leggy Bugs--Centipedes and Millipedes”).

One nice image I found was helpful with identifiers. View a nicely captured example of movement at "Close-up Caterpillar Footage".

My image shows a caterpillar with two possible paths to adulthood of butterfly or moth. The pupa stage is chrysalis or cocoon. A butterfly emerges from a chrysalis, and a moth emerges from a cocoon. Their antennae and body shapes differ. Butterflies are active in the daytime, while moths are active at night.

North Carolina State University's "Lepidoptera" site succinctly describes the order that butterflies and moths belong to:

The name Lepidoptera, derived from the Greek words "lepido" for scale and "ptera" for wings, refers to the flattened hairs (scales) that cover the body and wings of most adults.”

The site includes basic information about the caterpillar life cycle and the adult stages as butterflies and moths. It also discusses animal classification terminology, noting that Lepidoptera is a category (order) under Insecta (class). It also summarizes subcategories (families) of lepidoptera. One family, Geometridae, includes inchworms. (Their locomotion is so weird to me that I'm going to save writing about them in my next article.)

I’ve always wondered about caterpillars having many legs, yet emerging as butterflies or moths after complete metamorphosis, with only six legs. For differentiation between complete (four-stage) and incomplete (three-stage) insect metamorphosis, visit the Pacific Science Center Exhibits “Metamorphosis” site.

Another curiosity for me is that “caterpillar” is their larval term, whether they emerge as either of the flying insects. Swithzoo’s "Caterpillar" site explains: “The caterpillar's six front legs transform into the adult insect's legs, the other 'prolegs' disappear, wings grow, and the insect emerges as a beautiful moth or butterfly.”

Purdue’s “Is It a Moth or Is It a Butterfly?” elaborates on the caterpillar’s prolegs and other characteristics:

Caterpillars have a well-developed head and a cylindrical body, which is made up of 13 segments. Each of the three segments behind the head has a pair of legs, just like adult insects. But caterpillars also have some additional, fleshy, leg-like appendages - called prolegs - on other segments. Prolegs have tiny hooks at the end that function to grasp things such as the stems and leaves of plants.

The Library of Congress site “How can you tell the difference between a butterfly and a moth?” provides loads of helpful, short, section titles about these insects (wings, anatomy, behavior, cocoon/chrysalis, …).

Backyard Nature's site "Caterpillars” shows an image that indicates the site’s focus on these animals’ voraciousness—webpage title imaged as leaves chewed into contours of “CATERPILLARS”. Visit for close looks and reads about these leggy bugs.

More resources:

• GardeneGateeNotes “Cocoon versus chrysalis”
  This site shows a cocoon and chrysalis side by side and provides a short, nuts and bolts explanation.
• Diffen's "Butterfly vs. Moth"
  This site has a handy two-column table at the top, then more details and images. This site also includes a Related Comparisons section with links to pages comparing other related insects, other similar animals.
• Easy Science for Kids "Butterflies and Moths"
  A table near the top shows differences between moths and butterflies, followed by basic text and a diagram (parts identified) for those who are just starting to look into these flighty insects.
• Brittanica Kids site
  The main attraction is a helpful diagram of a butterfly and moth side-by-side and corresponding parts identifiers.
• Kids' Inquiry of Diverse Species site for “Butterflies and moths”
  This site’s format is question-and-answer, with basic and elementary approach.
• “Moths vs Butterflies”
  Entertaining video (mostly narration) of basic contrasts between these flyers.

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Leggy Bugs articles:

• Centipedes and Millipedes
• Caterpillars (Lepidopteran Larvae, which Become Butterflies and Moths)
• Inchworms
• Crane Flies
• Daddy Longlegs
• Walking Sticks
• Praying Mantises
• Huntsman Spiders
• Grasshoppers