In the garden: Questions about bagworm

Chad Frey
The Kansan

 I have been getting questions about when to spray for bagworm.   If you recall last year we had a tremendous population of these critters, maybe the worst I’ve ever seen.  Most calls on how to control bagworms come in during late-July to early-August when damage appears. Bagworms are difficult to control when they are that large.  They are much easier to kill while small.

A mature bagworm hanging on an evergreen tree

Bagworms overwinter as eggs inside the dead female’s bag. Young larvae normally hatch and emerge during mid to late May in Kansas. Now would be a good time to use control measures. However, make sure the bagworms are present by looking for a miniature version of the mature bagworm. Also, check to be sure the bagworms are alive before spraying. Predators and parasites can sometimes naturally control this pest.

The ends of many branches may have woody-looking clusters that look like they were a natural part of the trees. These are Evergreen Bagworms.

Insecticides commonly used for controlling bagworms include:

acephate (Orthene)

permethrin (38 Plus Turf, Termite & Ornamental Insect Spray; Eight Vegetable, Fruit & Flower Concentrate; Lawn, Garden, Pet, & Livestock Insect Spray)

cyfluthrin (BioAdvanced Vegetable and Garden Insect spray)

bifenthrin (Bug Blaster II, Bug-B-Gon Max Lawn and Garden Insect Killer)

lambda-cyhalothrin (Spectracide Triazicide, Bonide Caterpillar Killer)

spinosad (Conserve; Natural Guard Spinosad; and Captain Jack's Dead Bug Brew)

Spinosad is an organic control that is very effective on this pest.

Thorough spray coverage of foliage is essential for good control with any of these products.

Scott Eckert

— Scott Eckert is a Kansas State Research and Extension Agent for Harvey County. Horticulture is his specialty. He can be reached at 316-284-6930.