Skip Navigation

University of Nebraska–Lincoln

UNL Extension in Lancaster County

Horticulture

UNL Extension — helping you turn knowledge into "know how"

New VideoYouTube Video. Featuring photos of bagworms on a variety of plants.
Photos taken Fall 2008 in Lancaster County, Nebraska. Updated 03/12/09

Important: Read before choosing more videos at the end

Bagworm Control

by Mary Jane Frogge, UNL Extension Associate

Click to email this page to a friend.email this page to a friend

Bagworms have become an increasing problem in Lancaster County, Nebraska and surrounding areas. Last year, Lancaster County Horticulture Extension staff and Lancaster County Master Gardeners received hundreds of calls on bagworms. They can severely defoliate and kill evergreens, such as spruce and junipers. Bagworms may also feed on shade and ornamental trees, fruit trees, ornamental shrubs and perennial flowers. Since deciduous plants grow new leaves each year, the defoliation caused by the feeding usually does not kill them.

Please take the time to inspect your landscape for bagworms. Mature bagworms are small, one to two inch long, brown bags covered with dead plant material and tightly attached to twigs.

The overwintering bags contain as many as 300 to 1000 eggs each. Removing the bags before the end of May can help reduce their summer populations. Crush the bags or place them in the trash in a sealed trash bag. If bags containing larvae are discarded on the ground, the larvae may return to host plants after hatching.

Once the eggs hatch in early June, large bagworm populations can completely defoliate and kill evergreens during summer. Light infestations slow the growth of evergreens and lower their windbreak value and aesthetic appearance.

Lifecycle


Bagworm Close - on a Concolor Fir
Inspect, remove and dispose of bagworms.
Crush the bags or place in trash in a sealed
bag. Don't discard bags on the ground.

Bagworm eggs hatch in late May and early June. Young bagworms are as small as one-eighth inch long and can be difficult to see. After hatching, the larvae emerge from a hole at the base of the bag and spin down a strand of silk. The tiny insect is often caught by the wind and ballooned to nearby plants.

Once a host is found, larvae begin to form a new bag around their body. The larva is a brown or tan caterpillar with black markings. Larvae remain in their protective bag, sticking their head out to feed.

Bagworm larvae feed up until late August. The mature larvae then attach their bag to a branch with a strong band of silk and begin to pupate. Adult males emerge in September. They are small, furry gray moths with clear wings. The adult female does not have wings and never leaves the bag. After mating, the male moth dies. The female dies in the bag, mummified around the egg mass that overwinters until the following June.

Chemical Control


Insecticide control needs to be aimed at young larvae in mid to late June to be effective. Spraying trees is expensive. To get the best control for windbreaks or large stands of trees, late June to early July is the best time to apply insecticides for bagworm control.

Feeding by mature caterpillars slows in August before pupation into adults, so chemical control in late summer and fall is not effective.

Bacillus thuringiensis is available at nurseries and garden centers as Dipel or Thuricide. Other insecticides currently labeled for bagworm control include acephate, carbaryl, cyfluthrin, malathion and permethrin. Affected plants must be thoroughly covered with the insecticide in June so the insects ingest it as they are feeding. Be sure to read and follow all label directions.

Free printable brochure on bagworms and their control includes color photos, life cycle, control information.



(This resource was updated February 2009. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement)

YouTube

About YouTube: At the end of the video on Bagworms in Lancaster County, Nebraska, you'll see more videos available on YouTube. UNL Extension in Lancaster County takes no responsibility for, or exercises no control over, the organizations, views, accuracy, copyright or trademark compliance or legality of the material originating outside of the University of Nebraska-Lincoln Extension system.



University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office


Contact Information

University of Nebraska-Lincoln in Lancaster County
Web site: lancaster.unl.edu
444 Cherrycreek Road, Suite A, Lincoln, NE 68528
| 402-441-7180