Thyridopteryx ephemeraeformis

Bagworms are the larvae (caterpillars) of a native moth. The caterpillars develop within silk bags festooned with pieces of their host plants. As the caterpillars mature, they begin weaving more host plant debris into the silk, which provides structural stability as well as highly effective camouflage.

Curtis Young (OSU Extension, Van Wert County) showed participants in this week’s BYGL Zoom Inservice pictures of the parasitoid wasp Itoplectis conquisitor (family Ichneumonidae). The wasps were all males, and they were milling around on this season’s bagworms (Thyridopteryx ephemeraeformis, family Psychidae) in northwest Ohio.

 

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Bagworm caterpillars have “tied off” and are pupating in southwest and northeast Ohio. This marks a significant transition period in management options. Insecticides are no longer effective, but plucking remains viable.

During this week’s BYGL Inservice, participants noted that Bagworms throughout Ohio have reached a point in their seasonal development where they are becoming noticeable. This is prompting questions to Extensioneers on managing bagworms in landscapes and Christmas tree plantations.

Bagworms (Thyridopteryx ephemeraeformis, family Psychidae) are the larvae (caterpillars) of a native moth that develop within silk bags festooned with pieces of their host plants. As the caterpillars mature, they begin weaving more host plant debris into the silk, which provides structural stability as well as camouflage.

This Alert is based on a site visit that I made yesterday and centers on the common misconception that bagworms only feed on evergreens. Although bagworms are frequently called "evergreen bagworms" in many southern states, the caterpillars may feed on over 125 species of evergreen and deciduous woody plants in 45 plant families.

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 (family Psychidae) are so-named because the native moth caterpillars live in silk bags festooned with plant debris. It’s the perfect camouflage allowing them to remain undetected until their damage is revealed by their voracious appetites. The “bagworm season” is ending with the caterpillars transitioning from life in a tote bag to life in a sleeping bag.

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.