Bagworm Appearance Due – Winter May Have Reduced Numbers

Bagworm egg hatch should be underway in Central Kentucky. This normally occurs following the accumulation of 650 to 750 degree-days (base 50F). Eggs survive the winter in the bags that contained last year’s females. While the bags protect eggs from predators and cold, bagworms are not the hardiest of insects. The arctic vortex may have taken a significant toll on them. However, there may be enough survival on heavily infested trees and shrubs to cause some damage.

Figure 1. This newly hatched bagworm caterpillar has already started its shelter and is feeding on an oak leaf. Early damage is confined to the upper leaf surface. (Photo: Lee Townsend, UK)

Figure 1. This newly hatched bagworm caterpillar has already started its shelter and is feeding on an oak leaf. Early damage is confined to the upper leaf surface. (Photo: Lee Townsend, UK)

Management

Bagworms are a nemesis because damage can be significant unless a good control strategy is followed.  Four important elements are:

1)      Effective spray timing.

2)      Thorough spray coverage – be sure that the insecticide application reaches deep into the canopy or shrub. Treatment of just the outer foliage will not reach bagworms feeding deeper in the plant structure.

3)      Treat all infested trees and shrubs, not just ones that are heavily infested.

4)      Finally, apply a follow-up or clean-up treatment about 2 weeks later to control bagworms from late-hatching eggs. A number of effective products are available for bagworm control. Using them effectively provides the best results.

 

By Lee Townsend, Extension Entomologist

Posted in Forest Trees, Landscape Trees & Shrubs