This critter is the larvae of a moth that builds a brown bag which is attached to twigs of trees. During the summer, a dark brown to black caterpillar can be found inside the bag which it carries along as it feeds on leaves. Late in August, the caterpillar pupates and in a few days the adult moth emerges to lay eggs for next year's generation.

Evergreens such as arborvitae or cedars may be severely damaged or even killed by an infestation of bagworms while deciduous trees are rarely threatened.

The most obvious sign is the presence of small brown bags on your plants.

 
 

Since these are true caterpillars, the biological control called Bacillus thuringiensis (Bt) is one option for control. Other insecticides are also labeled for bagworms.

If there are just a few bags on plants at reachable levels, just hand pick them and soak them in a pail of soapy water or otherwise destroy them.

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.

 

Types of Insects

"Name That Bug Page"

 

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