While you may be familiar with baguettes and bagpipes, you may not know about bagworms.
The Brazos Valley has experienced unusually high numbers of bagworms this year. While the larvae or caterpillars of this insect can damage deciduous shrubs and trees, they can spell disaster for evergreens.
This pest is often confused with webworms also known as tent caterpillars, which spin large spidery webs that encompass entire tree branches. Tent caterpillars defoliate trees, especially pecans, and are quite obvious.
In contrast, the most noticeable stage of bagworms resembles small Christmas ornaments hanging from a branch and may go unnoticed. The bagworms live inside these tough, silklike cases that they cover with bits of twigs and leaves from the host plant.
Adult bagworms are an inconsequential-looking moth. In fall, female moths deposit 400 to 1,000 eggs in the bag; then the females drop to the ground and die. Their eggs hatch the next spring.
Less than 1/16 of an inch long, the baby caterpillars initially move around by drifting with the wind on a long silk streamer. As the caterpillar grows, so does the bag. In the final stage, it is usually 1 to 2 inches long and a half-inch wide. The caterpillars may pupate in August or September and after a few weeks, adult moths emerge.
Bagworms -- common on arborvitae, red cedar and cypress -- can severely damage evergreens because leaf loss can kill branches.
"Texas has several species of bagworm. Each species' slightly different habits and life cycles affect the timing of control measures," Extension entomologist Bart Drees says. "Each species has one generation per year." The territory of the bagworm Thyridopteryx ephemeraeformis, found on most evergreens, ranges from the Oklahoma-Texas border to the Gulf Coast.
While bagworms have some natural enemies such as birds and insect predators, hand picking the bags off of plants is the most economical and environmentally safe way to control them. Because eggs in bags thrown on the ground will hatch in the spring, seal the picked bags in a container and put it in the trash.
If hand-picking is not practical, use an insecticide labeled for bagworm control. Drees says to apply insecticide soon after bagworm eggs have hatched or while the larvae are small and feeding. He gives this tip for knowing when the timing is right: Collect the bags in late winter and keep them in a container out of sunlight. "Once the caterpillars hatch from the bags, apply insecticide to plants," Drees says.
For more information about bagworms and specific insecticide recommendations, visit the Extension website landscapeipm.tamu.edu/ornamentals/trees_shrubs/bagworms.html.
* Charla Anthony is the horticulture program assistant at Texas AgriLife Extension, Brazos County, 2619 Texas 21, Bryan, Texas 77803. Her e-mail address is charla.anthony@theeagle.com.
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