The evergreen bagworm, as its name implies, is well known for its ability to defoliate evergreen trees and shrubs like spruce, arborvitae, fir, junipers and pine. When given a chance, it will also feed on deciduous trees like maples, honeylocust, and crabapples. In late May and early June bagworms hatch from eggs that overwinter in the bag of their mother. When young bagworms begin feeding on broadleaved plants the caterpillars are too small to feed all the way through, so they leave circular patterns of skeletonization. Bagworms can be easily controlled with a spray application of spinosad (Conserve, or Fertilome borer and bagworm killer), or Bacillus thuringiensis (Dipel). More control options are available on the Purdue Tree Doctor App, purdueplantdoctor.com.
View this video located on the Purdue Plant Doctor App Suite Facebook page to watch a young bagworm caterpillar poke its head out of its silken bag to feed on a maple leaf. The young caterpillar scrapes the leaf surface to feed, and cuts bits of green tissue and glues it on its back. At the end of the video it sticks out its legs and flips the entire bag over to hide from the lights.
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Lindsey Purcell, Urban Forestry Specialist
Purdue University, Department of Forestry and Natural Resources
Lenny D Farlee, Sustaining Hardwood Extension Specialist
Purdue University Department of Forestry and Natural Resources
Cliff Sadof, Professor
Purdue University Department of Entomology