Guide

Look closerInsects

Giant silk moth cocoons on bare twigs

November to March

Once the leaves fall, the papery cocoons of giant silk moths, such as the cecropia and the promethea, can be spotted on shrubs and twigs. A cocoon may hold a pupa that waits out the winter and emerges as an adult moth in late spring.

Why this time of year

Once the leaves are down, cocoons that were hidden all summer show against bare twigs, and they stay put through winter.

How to notice it

  1. Pick an edge with bare shrubs and young trees, such as a power-line cut or a trail edge. Look at twigs from knee height up to just above eye level.
  2. Look for a brown, papery bag attached firmly to a twig. That is a cecropia cocoon. Some are puffy and some are tight and compact.
  3. Look for a single curled dead leaf that hangs from a twig tip by a stem wrapped in silk and does not blow away. A promethea cocoon is wrapped inside it. Try sassafras, spicebush or tulip tree if you have them nearby.
  4. Look, do not pick. Take a photo and leave the cocoon where it is, because a moth may be inside and needs it until spring.

Try this with kids: Can you find one dead leaf that is hanging on by a stem wrapped in silk when all the other leaves are gone?

Word to know: “Pupa”: the resting stage inside a cocoon, between caterpillar and adult moth.

Safety

  • Check for ticks after walking through shrubby edges, and stay off trail edges along roads or active power equipment.
  • Do not collect or cut cocoons: the pupa inside can be killed.

Sources

  • pmc.ncbi.nlm.nih.govPeer-reviewed paper on cecropia cocoon dimorphism: cocoons collected in Central and Eastern Massachusetts Dec-Mar 2013-2016 on mid- to low-lying shrubs in disturbed areas along trails and power lines; baggy and compact cocoon forms; cocoon is overwintering housing for the pupa.
  • northernwoodlands.orgNorthern Woodlands Outside Story: cecropia cocoons drab papery brown, firmly adhered to branch; look up just above eye level; promethea spin cocoons at branch tips reinforcing the leaf petiole with silk so the leaf hangs all winter; promethea hosts tulip tree, sassafras, spicebush.
  • val.vtecostudies.orgVermont Center for Ecostudies Cocoon Watch: cocoons attached to branches of trees or bushes; November stick season is the time to look; giant silk moths have declined over past decades across the Northeast.
  • val.vtecostudies.orgVCE 2021 results: over 100 cocoon observations of four species in Nov-Dec, over half by one observer (findable but not common).

Checked against these sources on October 6, 2026.

In the guide for November, December, January, February, March

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