Bagworms are starting to become very noticeable right now as they are defoliating many arborvitae, junipers, spruce, and other trees and shrubs. Bagworms are often overlooked in these trees because they build bags out of needles of the trees and they almost resemble a pine cone.
Bagworms are very common in Indiana. In June, they hatch from eggs and start to build new bags to live in. The caterpillars will crawl partially out of the bags to feed, but at the site of danger they will retreat into their sanctuary. Each female bag can produce over 1,000 bagworms, so populations and damage can occur rapidly. The bagworms will mature in August/September and the bags will be about two inches long. At this point, damage is becoming noticeable and they cannot be killed by any pesticide.