bagworm

This "bagworm season" which began in early June was marked by damaging localized infestations throughout Ohio. Images showing heavy defoliation from bagworms (Thyridopteryx ephemeraeformis) were commonly shared during our weekly BYGL Zoom Inservices. Populations appeared to be higher than has been seen for several years.

Overwintered common bagworm (Thyridopteryx ephemeraeformis) eggs are hatching in southwest Ohio. The 1st instar caterpillars are very small with their bags measuring around 1/8" in length.

This is the time of the year when Common Bagworms come into clear focus owing to their size and noticeable damage. Overwintered eggs hatched in southwest Ohio in early June (see "Be Alert to Bagworms!" posted on June 6). However, it's amazing how well these native moth caterpillars crawl below our radar until their burgeoning appetites finally gives them away.

Overwintered common bagworm eggs are hatching in southwest Ohio. The 1st instar caterpillars are very small with their bags measuring around 1/8" in length.

Most of the Common Bagworms I looked at yesterday in southern Ohio and central Indiana had initiated their annual "tie-off" in preparation for pupation. Bags are tightly closed and tied with silk to a twig or other anchorage point. This means the damage caused by these caterpillars wrapped in silk bags festooned with host plant debris is drawing to a close.

I'm not yet saying this is going to be a banner season for Common Bagworms. However, I'm commonly finding bagworms in southwest Ohio without much effort. I've not heard reports from elsewhere in the state

Overwintered Common Bagworm eggs are hatching in southwest Ohio. The tiny 1st instar bags are constructed with pieces of tan to reddish-brown sawdust-like frass (excrement) stuck to the outside of silk and look like "dunce caps."

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).