Moth Chrysalis Identification: Pupae, Cocoons, Look-Alikes

What people call a moth chrysalis is almost always a moth pupa, either wrapped in a silk cocoon or lying bare in the soil. Strictly, chrysalis is the name for a butterfly pupa; the word comes from the Ancient Greek for gold (Wikipedia, Pupa).

Moth pupae are obtect, meaning the legs, wings and antennae are glued tightly to the body, and they are commonly enclosed in a cocoon. Wikipedia describes moth cocoons as tough or soft, opaque or translucent, solid or mesh-like, and of various colours. Other moths spin no cocoon at all and pupate in an underground cell or loose in the soil.

The Amateur Entomologists' Society lists three places to look: attached to the food plant or something nearby, unattached among debris such as leaf litter, or in a silk-lined chamber underground.

• Covering. A butterfly chrysalis is naked; Wikipedia's butterfly article says it is not wrapped in a cocoon, unlike that of moths. Most moth pupae are in a cocoon or underground.
• How it hangs. A butterfly chrysalis usually hangs head down from the cremaster, a spiny pad at the rear end, and some species add a silk girdle that holds the pupa head up (Wikipedia, Butterfly). A moth cocoon is usually spun onto a surface: the cecropia moth's brownish-grey cocoon is attached by silk along its whole length to a twig (Missouri Department of Conservation).
• Colour. Butterfly chrysalises can be bright: the monarch's is jade green with metallic gold dots, 1 to 1.75 inches long (Xerces Society). The moth cocoons on this page are brown or grey silk, hairs or plant material.
• The cremaster alone does not decide it. Hawk moth pupae also have a cremaster at the tip of the abdomen (Wikipedia, Sphingidae), so check the covering and the place as well.

• Bare pupa in garden soil: often a hawk moth. Wikipedia says hawk moths usually pupate off the host plant in an underground chamber, among rocks or in a loose cocoon, and in some species the tongue case stands free of the body instead of being fused to it. Tomato hornworm caterpillars drop off the plant and burrow into the soil to pupate; the adult has a wingspread of four to five inches (University of Minnesota Extension).
• Long brownish-grey cocoon along a twig: cecropia moth. It overwinters as a pupa inside; the adult spans 3 3/4 to 6 inches (Missouri Department of Conservation).
• Brown silk cocoon wrapped in a leaf: polyphemus moth. Wikipedia says the leaves of the host plant are used for protection and camouflage.
• Tapered bag of silk and twigs hanging from an evergreen: evergreen bagworm. The case grows to over 6 cm, is open at both ends and is covered in bits of the host plant; the larva pupates head down inside it, and the wingless female never leaves it (Wikipedia).
• Cocoon made of the caterpillar's own hairs: the woolly bear, which overwinters as a caterpillar and pupates in a cocoon of its hairs before emerging in spring as the Isabella tiger moth (Missouri Department of Conservation). See caterpillar identification.
• Loose hairy cocoon in leaves near the coast of Maine or Cape Cod: possibly browntail moth. Leave it alone; see the safety section below.

• Where it was. Soil, leaf litter, a twig, inside a rolled leaf, a wall or a hanging bag. Each place narrows the list above.

• What wraps it. Nothing (bare pupa), silk, silk plus leaves, silk plus plant fragments, or hairs.
• How it is attached. Hanging by the tail with no cocoon points to a butterfly chrysalis; spun along a surface or buried points to a moth.
• Shape details. Look for a free tongue case standing away from the body (some hawk moths) and for the cremaster at the tail.
• Movement. Some moth pupae have sharp ridges called adminicula that let them wriggle out of their hiding place (Wikipedia, Pupa), so a pupa that twitches when touched is alive, not hatching.

Write down the plant it was on or under and the date. A pupa carries fewer visible marks than a caterpillar or an adult, so the most certain name often comes from the moth that emerges.

Anywhere from about two weeks to more than a year. Wikipedia says the pupal stage may last weeks, months or even years depending on temperature and species, and that in temperate regions pupae usually stay dormant through winter. The Amateur Entomologists' Society gives a few weeks to more than a year for the whole life cycle.

• Hawk moths: the pupa stays underground for about two to three weeks, and in most species the pupa is also the overwintering stage (Wikipedia, Sphingidae). Tomato hornworm moths emerge in about two weeks in summer, while pupae formed late in the season stay dormant in the soil through winter (University of Minnesota Extension).
• Cecropia moth: overwinters in the cocoon (Missouri Department of Conservation).
• Woolly bear: pupates in spring after overwintering as a caterpillar (Missouri Department of Conservation).

For comparison, a monarch butterfly chrysalis lasts 8 to 15 days in normal summer conditions (Monarch Joint Venture). A moth cocoon found in autumn that seems to do nothing for months is usually waiting for spring.

A caterpillar about to pupate usually stops feeding and leaves its food plant, which is why people find them crossing paths and walls.

• Monarch caterpillars at the end of the fifth instar crawl away from the milkweed, spin a silk pad and hang upside down in a J shape (Monarch Joint Venture).
• Hornworms drop off the plant and burrow into the soil (University of Minnesota Extension).
• Bagworm larvae wrap silk around a branch, hang from it and pupate head down inside the bag (Wikipedia).
• Woolly bears use their own hairs to build the cocoon (Missouri Department of Conservation).

If you find a wandering caterpillar, leave it where it can reach soil or cover. For the caterpillars themselves see moth identification and caterpillar identification.

Do not pick up hairy cocoons with bare hands. The Maine Forest Service says browntail moth caterpillars, pupal cocoons and shed skins carry microscopic toxic hairs that can cause a rash similar to poison ivy and/or trouble breathing, lasting from a few hours to several weeks. Wikipedia notes the hairs can blow in the wind and stay potent for up to three years.

If a rash spreads, or anyone has trouble breathing after contact, see a doctor or call your local poison control centre. Use gloves or a stick to move a cocoon you cannot identify.

Take one photo of the pupa or cocoon where you found it, one close-up from the side, and one showing the plant or surface it was on. Put a coin or ruler beside it for size. InsectLens will narrow the family from a pupa, and a second photo of the moth that emerges confirms the species.

Research and drafting for this page used AI assistance. Every figure, date and quotation was then checked line by line against the sources listed at the bottom of the page, each of which was opened while writing. Nothing here is a diagnosis or a treatment plan; if a bite, sting or rash worries you, or anyone has trouble breathing or swelling of the face or throat, get medical care straight away.