Bagworms


Who would suspect that those funny little brown clumps of leaves and twigs we see around the exteriors of our homes are actually moths? The bagworm Thyridopteryx ephemeraeformis belongs to the Order Lepidoptera although the females never develop wings and spend their entire lives inside their cases.
Also known as the Evergreen Bagworm, this pest is a common problem in landscape plants and urban forests throughout the eastern and central states. Although they like to munch on evergreens, they are general feeders and can defoliate many types of plants and trees. In the Florida Keys bagworms are making their homes out of seagrape leaves, and palm fronds to name a few. They consume entire leaves, usually one branch at a time, and can strip a plant to death.
Bagworms begin constructing their cases shortly after hatching, starting with silk and adding sand, soil, droppings, leaves, twigs, bark, and other fibers. The completed bag is up to two inches long. They carry this covering with them throughout their lives, protruding from the end to feed, crawl, or make repairs. Only the mature males, which are black with clear wings, emerge to fly off to mate. A female will lay hundreds of eggs in her bag before she dies. When the larvae hatch they disperse by crawling and in the wind. They undergo a complete metamorphosis before starting the cycle all over again.
Bagworms are controlled to some extent by natural predators. In the landscape, picking off and destroying the bags, especially those containing eggs, is recommended. Insecticides such as Dipel or Thuricide with the active ingredient Bt (Bacillus thuringensis)are effective if applied while small larvae are feeding.

Remember bagworms stuck on the side of your house are not getting the food needed to survive, therefore will die but the bag remains. It is easy to remove by hand picking or a strong stream of water or pressure washer.

For more information:

These links were updated in March, 2013.

Article written by Ellen Sculley, Monroe County Master Gardener and Kim Gabel UF/IFAS

Photo credits: Kim Gabel, UF/IFAS

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