Bagworms
Bagworms attack and defoliate most evergreen and deciduous trees and shrubs. However, they are particularly destructive to arborvitae, cedar, juniper and other ornamental evergreens. Bagworms live inside spindle-shaped bags, which they construct while in the larval or caterpillar stage. These bags are dragged wherever the caterpillars go for protection against their natural enemies.
Life Cycle
During winter, bagworms are in an egg stage inside a maternal bag, which is attached to a tree or shrub. The eggs hatch in late May or early June, and the small caterpillars begin feeding and constructing the bag in which they will stay. While feeding, the caterpillars crawl partially out of the bag.
As the caterpillars grow, so does the bag. The caterpillars mature in late August and September, pupate and emerge as adults. The female is a wingless moth that never leaves the bag. A winged male moth fertilizes her, then eggs are laid inside the bag and the female moth then dies. There is one generation of bagworms per year.
Control
Light bagworm infestations, particularly on shrubs and small trees, can effectively be controlled by hand picking the bags from the infested plants. These bags must be disposed before the eggs hatch in June. New plants should always be carefully inspected for the presence of bagworms before planting.
Half-grown to nearly full-grown bagworm caterpillars are difficult to kill with an insecticide. The key to successful control with sprays is to spray when the bagworms are small; therefore, timing is important. It will take two to three applications to get optimal results.
Contact your RYANPro for assistance controlling this landscape pest