I need a natural way to control bagworms. I have way too many trees to spray.

Answer #1 · John Heider's Answer · Hi Amy-Bagworm infestation can be quit a problem if they have infested a large number of trees or shrubs. Sometimes, hand picking of the bags or cacoons can save your trees and shrubs if most are accessable. It sounds as though your problem has gone beyond being able to remove most of the bags from numerous trees. Aside from picking the bags or complete removal of the tree, if infestation has gone beyond saving the trees, application of an insecticide I believe is your best choice. Insecticide control needs to be aimed at young larvae in mid to late June to be effective. Feeding by mature caterpillars slows in August before pupation into adults, so chemical control in late summer and fall is not effective. The life-cycle progression of this pest dictates the best time of the year for insecticides to be used.

Kansas State University has done research on this pest. This article may help you with a plan of action better than I could writing several paragraphs that may not be as interesting or helpful. You can Google this site at www.ksre.ksu.edu/library/entml2/mf728.pdf. I found there is one natural way of controling Bag Worms, there may be others, by planting certain flowering plants near by that attract a wast, not the scary biting kind, that will feed on the bagworm.

This article you can Google at “Conservation Biological Control in Urban Landscapes: Manipulating Parasitoids of Bagworm (Lepidoptera: Psychidae) with Flowering Forbs.”

Bagworms are not very prevalent here in Southern Calif. as it is in the East. Hopefully others may have had practical experience with this pest that will add to this information in order to rid you of this problem.)

Answer #2 · Brent Wilson's Answer · Hi Amy - Sorry to hear you have a problem with bagworms in your landscape. Not sure how bad it really is: whether it's just a few here and there, or a serious infestation?

If it's just a few the best natural way to control them is, like John said, by picking or cutting them off the plants or trees.

If it's a serious infestation handpicking is not an option. This leaves you with chemical control. I've never had a serious infestation of bagworms in my landscape but have helped several customers at our nursery over the years to deal with the problem. There's Talstar 1, which is probably the most effective chemical for use in controlling bagworms, but some have been successful using permethrin-based products. Permethrins are non-synthetic products but still are listed as toxic to humans.

If you do decide to use a pesticide, these would be used in late spring. If you wait too long though the cocoons will be too tough for pesticides to penetrate. These chemicals are sprayed on the tree and will kill the caterpillar when it emerges from the cocoon and starts to feed. Keep in mind that these products will only be effective when the larvae are feeding.

If there's an infestation, this is a serious problem as they can damage your plants and trees. The best advice I can give you is to contact your local arborist to see if he/she can help eliminate these pests.

Good luck!)