Link to Caterpillars in Your Yard and Garden Bagworm caterpillars (Thyridopteryx ephemeraeformis) are present from early June to August. They produce one generation per year.
Link to Caterpillars in Your Yard and Garden

Caterpillars are found within conical, silk-lined bags or cases they construct from bits and pieces of the host plant. The bag is carried about as the caterpillar feeds and is enlarged as the caterpillar grows. The full-grown larva is about one inch long, and the head and thoracic regions have a mottled brown appearance. It is difficult to pull the caterpillar from its bag without damaging its body. Host plants include both conifer and hardwood plants, with preference for white and red cedar. This caterpillar is an important pest of many shade trees and ornamental shrubs.

About the family

Bagworms are in the Psychidae family.