Bagworms In The Garden

Bagworms if left untreated can do major damage to your yard.

They can be hard to see when a tree is activly growing. They camouflage themselves with bits and pieces from the plant they're on.

Bagworm Facts

Thyridopteryx ephemeraeformis is their latin name. I won't even begin to try and pronounce it!

Male bagworms are the caterpillar stage of a moth. Females don't become moths, they stay in the caterpillar stage. While the males do morph into a moth, the moth is very rarely seen. You are more likely to see the female and her bag than the male.

They make distinctive bags on a variety of trees and shrubs.

They can be found on both evergreen and deciduous trees and shrubs. They prefer evergreens but will hang from any type of tree or structure. I saw one confused little one climbing up a flag pole.

If you see brown sections on an evergreen you should look closer to see if they are being caused by bagworms.

Life Stages

The female lays between 500-1000 eggs inside the bag before she dies. So you can see how one bagworm can soon become a huge problem!

The eggs overwinter inside the bags. They hatch sometime around mid May to early June. The larvae crawl out of the bag and start eating leaves and needles.

bagworm They will use silk and pieces of material from the plant to construct their own bag. You can actually watch them dragging the bag around as they eat up the leaves. If you poke at them, they'll retreat into the bag. The bag starts out small but as the bagworm grows, the bag will grow in size too. The mature size of the bag is between 1-1/2 to 2 inches long.

In late summer the bag is permanently attached to a branch and the worm transforms into their respective adult stages.

An adult male will emerge in early fall. Males which are small moths will fly in search of a female.

bagworm The female stays inside the bag. She stays in the pupal stage and doesn't become a moth. She's more like a grub and varies in color from creamy white to black.The male will mate with the female through an opening at the bottom of the bag. The female will then lay her eggs and die. The eggs will overwinter in the bag and emerge in May to start the cycle again.

Larvae may spin a silk thread and get flown over to another plant by the wind or they may crawl around the plant they were born on.

Overpopulation can happen in a few short years!

Integrated Pest Management

Hand picking is by far the best method of insect control for bagworms. You can easily see them on deciduous trees after the leaves have fallen.

Pick the bags off the tree and put into a trash bag that you seal and dispose of. If you just pick them and toss them on the ground, they'll emerge in the spring and crawl to a plant. If you try to squish them by stepping on them you won't get all the eggs destroyed.

If your infestation is large or they are too high up in the tree to hand pick you can spray them with an insecticide. The time to spay is in late May early June after they have emerged and before they get over 1/2 inch long. Sprays will not penetrate the bag but more importantly they aren't eating after they've reached over an inch long.

Insecticides* such as Sevin and BT (Bacillus thuringiensis)are effective against young bagworms. Foliage should be throughly wetted with the insecticide. You won't be killing them by soaking the bag. They'll need to eat leaves and needles that have the insecticide on them.

When spraying any insecticide always read and follow directions on the label. And if spraying is done overhead protect your eyes and face from drifting spray.

*Pesticide recommendations are provided only as a guide. It is the applicator's responsibility, by law, to read and follow all current label directions. Planandplant.com assumes no liability resulting from the use or misuse of these recommendations.

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