Cocoon vs chrysalis — what’s the difference?
A cocoon is made by moth caterpillars. They spin silk around themselves before they pupate. A chrysalis is what butterfly caterpillars form — no silk, just a hardened outer shell. Both protect the pupa while it transforms.
How long different caterpillars stay in their cocoon
| Species | Type | Time inside |
|---|---|---|
| Monarch butterfly | Chrysalis | 10–14 days |
| Black swallowtail | Chrysalis | 9–14 days, or overwinters |
| Painted lady | Chrysalis | 7–10 days |
| Cabbage white | Chrysalis | 10–14 days |
| Silk moth (Antheraea polyphemus) | Cocoon | 2–3 weeks, or overwinters |
| Luna moth | Cocoon | 2–3 weeks, or overwinters |
| Hawk moth (Sphingidae) | Underground pupa | 2–4 weeks, often overwinters |
Why some take much longer
Many species use the cocoon to wait out winter. They enter a state called diapause, slowing their metabolism almost to a stop. They emerge when the temperature, day length, and humidity match spring conditions — sometimes after 4 to 9 months inside.
Signs the moth or butterfly is about to emerge
- The chrysalis becomes clear or dark as wing patterns become visible.
- Movement inside in the day or two before emergence.
- Most emergences happen in the morning so the wings can dry before evening.
If you found a cocoon outdoors
- Leave it where it is if possible.
- If you need to move it, keep the orientation and place it in a sheltered, ventilated spot at the same outdoor temperature.
- Don’t bring it indoors in winter — warmth tricks the moth into emerging with no food source available.
Not sure which caterpillar you found? Try our free bug identifier with a photo.