Bag Worms

If you were to walk down the street and ask someone, “what do bag worms mean to you?” you would probably receive a blank stare and maybe a few whispers questioning your sanity as people tried to avoid you. However, if on that same street you were to run into an avid gardener, they would tell you bag worms mean one thing: trouble!

Bag worms are small caterpillars found throughout the Eastern United States. The main sources of nutrition for the bag worm are both deciduous and evergreen trees. In particular, they enjoy feasting on a buffet consisting of juniper, spruce, arborvitae, pine and cedar.

UPDATE! All About Worms has partnered with HealthLabs so that
you can get tested for parasites at a fully-qualified lab near you,
no doctor's visit required
! Check it out at!

The bag worm derives its name from the silk bag that is attached to their body near the hindquarters. As the season progresses and the bag worms have almost eaten through your entire backyard the silk bag becomes large enough for the worm to retreat into to avoid danger. One can actually see pieces of the host tree woven into the silk bag on the caterpillars’ backside.

The emergence of the bag worm usually takes place around June or July. One bag worm in a tree is not necessarily a problem. It is when one bag worm invites his entire family and extended family over for a meal that it becomes a major issue. An excessive amount of bag worms destroys the tree or trees over a season by defoliation.

A complete removal of bag worms is possible and there are two basic methods, by hand or by chemical. If you see only one or two bag worms it is recommended that you remove them by hand and preferably before they hatch in June or July. If there is an infestation, however, chemical spraying is necessary.

No Paywall Here!
All About Worms is and always has been a free resource. We don't hide our articles behind a paywall, or make you give us your email address, or restrict the number of articles you can read in a month if you don't give us money. That said, it does cost us money to pay our research authors, and to run and maintain the site, so if something you read here was helpful or useful, won't you consider donating something to help keep All About Worms free?
Click for amount options
Other Amount:
What info did we provide for you today?:

Bag worms can be kept under control if you are careful. The key to avoiding a bag worm infestation is to keep a vigilant watch over your trees and to take immediate action if a bag worm is identified.

Recommended reading (click on the picture for details):
The Worm Book: The Complete Guide to Worms in Your Garden

Leave a Comment (but to submit a question please use the "Submit a Question" link above; we can't respond to questions posted as a comment)

Menu / Search

All About Worms