With this in mind, you can call a professional tree spraying company or go ahead and treat them yourself. Here is the info you need before tackling the job.

There are three main types of bag worms in the United States:

1. * Evergreen bagworm
   * Snailcase bagworm
   * Grass bagworm

Each type of bagworm creates a specific type of bag relative to its feeding habits. Most of the information here is about the evergreen bagworm.

BagWorm Life Cycle

Bagworms survive winter as eggs inside a tear-drop shaped bag found on a variety of trees and plants. The Evergreen Bagworm prefers evergreen trees and shrubs such as the blue spruce, arborvitae or cedar. There can be more than 800 eggs in each bag and they emerge as larvae in May. The larvae then use a combination of silken secretion and parts of the plant to create the bag around themselves. If you look at the bag of the everygreen bagworm, it looks a lot like the plant it is infesting.
Some people also mistake the bagworms as pine cones.
Most of their feeding and munching is done during this larval stage.

In later summer and fall, when the bags are around two inches in length, the larvae suspend the bags pointing downward from twigs during which time they transform into the pupae or ‘resting stage’ before becoming adults. (adults are moths)
Larvae Stage Bag Worms

As young larvae Evergreen Bagworms spin strands of silk that carry them from pant to plant where they feed. This is how they spread from plant to plant and why it is so important to eradicate them quickly.
When threatened, larvae will retreat inside their bag and hold the opening closed. The larvae feed on needles on conifers (evergreens).
In Ohio and the Midwest, you mostly find them on: junipers, spruce, pine, willow, apple, maple, elm, birch and cedar trees.

If the infestation is concentrated, they can completely defoliate a small shrub in about 2 weeks. Leaf damage is usually noticeable in starting in June and worsening in August.

How to Eliminate Bagworms in Your Landscape

When infestations of bagworms are diagnosed early (like June), control is fairly easy. Once population numbers begin to multiply and spread to numerous locations, control will be tougher but still possible. If bagworm infestations are not noticed until late summer, not only will their numbers be higher but the bagworms will have grown enough to make them more difficult to kill with an insecticide. The thicker the bag, the tougher the kill!

The quickest way to reduce their populations is to pick the actual bags off the trees and throw them into your fire pit. However, you can’t always reach all the way to the top of those arborvitae so you will need to spray an insecticide.
Talstar is a great insecticide (and the main one I recommend) with low odor that can be used. You will need to mix it in a pump sprayer. Always follow the directions!
If Bag Worms are infesting your trees and shrubs, you need to take care of them immediately.