Bagworms on Spruce

BYGLers reported during yesterday’s Tuesday morning BYGL Zoom Inservice that overwintered Bagworm eggs are hatching or have hatched in Ohio meaning the “bagworm season” is now underway. Look closely at trees and shrubs festooned with last season’s bag abodes to detect newly hatched bagworms.

Overwintered Bagworm (Thyridopteryx ephemeraeformis) eggs are hatching in southwest Ohio meaning the “bagworm season” is now underway. Look closely at trees and shrubs festooned with last season’s bag abodes to detect newly hatched bagworms.

Common bagworms have been with us for a while. Overwintered bagworm eggs began hatching in southwest Ohio at the end of May (see “Bagworm Eggs are Hatching: The Game’s Afoot!,” June 1, 2022). However, it’s amazing how long these general defoliators can continue to crawl below our radar as they chomp on evergreens and deciduous trees and shrubs before their cumulative damage and size finally make them apparent.

The vast majority of Common Bagworm caterpillars in southwest Ohio have initiated their annual "tie-off" in preparation for pupation. Bags are tightly closed and tied with silk to a twig or other anchorage point. Likewise, male bagworms in the northwest part of the state have tied-off; however, some female caterpillars are continuing to feed.

As summer draws to an end, many insects and mites approach the end of their seasonal activities as well. Curtis Young reports that the majority of common bagworms (Thyridopteryx ephemeraeformis) have finished their destructive feeding as caterpillars in their individual bags, have tied their bags to their host plant, and are pupating (pupa=3rd stage of their life cycle).