The bagworm is a pest native to the eastern United States that is invading our region's landscapes. It moved around mostly undetected, until a brown bag is noticed or plants start defoliating and showing signs of stress.
The local population of bagworms is booming and is expected to continue to grow over the next couple years. Because they are not particularly mobile, and each bag can hold around 300 eggs, the bagworm can quickly take over a yard or neighborhood. A few bags on trees or shrubs now can explode into hundreds the next season.
What plants do they like?
Bagworms prefer evergreens, especially arborvitae, but they are not limited by what they eat. They are most commonly found on pine, spruce, juniper, willow, honeylocust, black locust, elm, maple, oak, and popular trees. Over the last season we also spotted them on dawn redwoods, zelkovas, cherries, and several varieties of shrubs.
As the larva matures it begins to attach pieces of the leaves to the bag. Because they use bits of plant material the exact size, shape, and apperance of the bag can differ between plant species. By the time the larva is done feeding the bag typically reaches 1-2.5" in length.
How to control?
As mentioned earlier, bagworms can be hard to control because they are not often noticed until they are mature and safely hiding in their bags. However, they are manageable and treatable. If there are just a few bags, and are in reach, they can be picked off. When picking off the bags, be sure to remove the silk thread that attaches the bag to the branch. If this is not removed it can girdle and damage the branch later on. To destroy the bags, either squish the larva or cut them open before disposing of them.
If your plants are heavily covered or have several hard to reach bags, then spraying will be the best option. To effectively kill the larvae, they need to be sprayed in June after they have hatched and are actively feeding. Sevin (red bottle with yellow label) is one of the best products for killing bagworm larvae.
Contact us for help
If you know you have bagworms, or suspect you do, call us at 419-287-4679. We can help you find the correct product to treat them, or spray them for you. Because of the large population last year, we are expecting even more bagworms this year. Pay close attention to all of your plants, even if a bag is laying on the ground it could still have live eggs inside.
OSU Extension Fact Sheet
Some information was gathered from the OSU Extension Fact Sheet 'Bagworm and Its Control'. Follow the link for more information about its life cyle and habits.
While we strive for complete and correct information, not all plants grow true to their form and can not be guaranteed to grow as described.