How and when to treat bag worms that are attacking spruce trees?
Bagworms are insects that can defoliate evergreens and sometimes deciduous trees/shrubs. Mechanical control involves handpicking during the winter and before eggs hatch in June and disposing of in soapy water. Remove any bagworms from the ground as they may be able to complete their life cycle. See our publication for more information and biological control http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG32_Bagworms.pdf