Elm Tree Bag Worms
Elm trees are members of the Ulmaceae family that are found in many parts of North America. These hardwood trees are susceptible to diseases and insect infestations which can affect the health and vigor of the tree. Bagworms prefer to attack juniper or cedar trees, but will infest the elm tree on occasion. This damaging pest is often responsible for defoliation of the tree. Does this Spark an idea?
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Identification
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Bagworms are caterpillars that are characterized by the brown, spindle-shaped bags they place on host trees. These bags are 1 1/2 to 2 inches in length and are made from silk and bits of plant material. Bagworms live in their bags, only leaving to feed during the late afternoon to early evening hours. This pest has a wide host range, which includes deciduous trees and shrubs.
Effects
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Bagworm larvae is responsible for the feeding damage to elm trees. Damage to trees is usually noticed during the late summer months. Young larvae feed on leaf surfaces, skeletonizing leaves. Mature larvae consume entire leaves at once. Heavy infestations of bagworms can defoliate an elm tree, causing reduced vigor. Elm trees that suffer several repeated defoliations can eventually die as a result.
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Monitoring
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Monitor your elm trees for signs of bagworms by looking for the brown, silky bags on the branches of your tree. Early spring and fall are the best times to search for bagworms before they hatch and the bags are large and easy to spot. Bags that appear old are signs of bagworms, as the female lays her eggs in the bag. Generally, the same trees are susceptible to repeated infestations of bagworms each year.
Control
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Controlling light bagworm infestations is best accomplished by removing the bags from the tree by hand and destroying them. Bagworms are susceptible to a large number of predatory insects that feed on them. Parasitic wasps feed on bagworm larvae, reducing their numbers. Chemical control methods are available at your local garden center for use in the treatment of bagworms on elm trees.
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