Bagworms Possibly Still Treatable

We earlier reported that bagworms have hatched and are feeding on a wide variety of trees and shrubs.

Reports and observations suggest the caterpillars are growing fast and are approaching the point where insecticide control will no longer be effective.  Check for bagworms and treat sooner rather than later if control is warranted.  Treatment before bags exceed 1/2-inch long is recommended because small larvae are more vulnerable to insecticides, and feeding damage is relatively minor.

Many home landscape insecticides are labeled for control of bagworm caterpillars in Iowa.  Bacillus thuringiensis formulations would have controlled small larvae but a synthetic insecticide may be needed to control larger larvae.  Acelepryn (chlorantraniliprole) is one of the insecticides registered to control bagworms and is bee-friendly.

Jack Van Laar, Decatur County Extension Director found bagworms crawling on the side of a USPS mail drop box at the Leon Post Office.  See photos.  A large infestation was on a nearby tree.  We hope they don’t find their way into the mail slot and get carried with the mail!

small bagworm on mailbox

Bagworm infestation


Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on July 27, 2018. The information contained within may not be the most current and accurate depending on when it is accessed.