Bagworms are a common juniper, arborvitae, and spruce pest in our area, but can also be found on a wide variety of deciduous plants. Bagworms are easily identified by the cone-shaped protective cover that surrounds them. The “bag” is made of silk and woven together with material from the host plant.
Bagworm damage on evergreens can be quite substantial. If an infestation goes unchecked it could lead to plant death. Evergreen trees rely on the needles to provide energy for multiple years. For example, a pine tree that loses one year worth of needle growth is losing 3 or years worth of energy production. Deciduous trees have auxiliary buds and replace their leaves fast enough to avoid any major damage. But complete defoliation year after year can stress trees.
Generally, the young larvae start feeding on the interior of the plant without much initial damage. As the caterpillar grows, so does its appetite. If there is a large population, they can seemingly defoliate trees overnight.
Bagworms typically hatch in mid to late May but it can take 4-6 weeks before all eggs hatch making them difficult to control with one treatment. Early June is usually the best time to observe the small bagworms and it is the best time to treat with insecticides.
slightly more expensive. Bt it is considered organic. Other products may be cheaper but may have more ecological impacts than just killing the bagworms.
Wellnitz Tree Care’s Plant Healthcare Technicians would be happy to do a site visit to determine what treatment method may be the best for you and your property.
310 Congress Street, Emporia, KS 66801 • 5709 SW 21st St., Suite 108, Topeka, KS 66604