Bagworms eat conifer species of trees and shrubs as their preference then moves to deciduous trees such as sweetgum, maple, hackberry, locust, and elm.
Originally found to be killing trees in Colorado as early as 2003, this is a newly recognized disease (2008) of primarily Black walnut (Juglans nigra) and caused by a fungus, Geosmithia morbida, that is vectored into the tree by the walnut twig beetle (Pityophthorous juglandis).