Bagworms are pests infecting shrubs and woody ornamental trees


Since their spindle-like, protective bags are made of silk, debris and portions of leaves, they're camouflaged and often go unnoticed until serious plant damage has occurred. 

What times of the year are bagworms active?

Bagworms survive the winter as eggs within the bag of the adult female. Eggs hatch in mid to late April (may vary by location), and the larvae begin to look for food. Larvae disperse by first producing silk stands that are attached to branches. 

In early August, adult males emerge as black moths with fuzzy bodies, while adult females remain wingless and never leave the bag. 

Which tree species are infested?

Bagworms attack more than 120 species of both deciduous and evergreen trees and shrubs. Some of the more popular hosts include:

  • juniper
  • arborvitae
  • cedar
  • spruce
  • honeylocust
  • linden
  • willow
  • maple
  • oak
  • birch
  • elm
  • poplar

What are the symptoms of a bagworm infestation?

Bagworm caterpillars consume the tree's leaves, and heavy infestations may lead to a tree being completely stripped of all leaves. In evergreens, no re-growth occurs and attacked branches often die. 

Management & Treatment

Management of bagworms by homeowners may involve hand picking. For the best results, make sure that all bags are removed and destroyed, since even one bag left behind could cause re-infestation. 

When hand picking is not practical, an insecticide treatment should be used. While spraying, thorough leaf coverage is critical. Two applications, two weeks apart, may be necessary for heavy infestations. 

Worried bagworms are hurting your landscape? Contact your local certified arborist for a consultation today! 

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