If you have junipers or arbor vitae in your landscape, you could have bagworms! To determine if you do have these little fellows in your plants, you can check for small, teardrop shaped bags or cases of tied-up plant material. These cases will be anywhere from ¼ to 1 inch in length. The larvae that are within the bags will emerge to feed on evergreens as well as deciduous trees and shrubs.
The overwintering larvae hatch in June and climb to the top of the plant. There, the tiny larvae send out a single strand of silk that is 1 to 3 feet in length. These strands are caught up in the wind and are carried wherever the wind may blow. Once they land on a suitable host plant, they often begin feeding at the top and work their way downward. You can find them commonly on spruces, junipers, arbor vitae, red cedar, cypress, oaks and crabapple trees. These insects have quite the taste for evergreens.
The bagworms spin individual silk tents and cover themselves with foliage from the host plant. They crawl out of the tents to feed on surrounding vegetation. They continue feeding through the summer and can cause extensive damage. The leaves on the plants will regrow, but the needles on evergreens don’t come back and the tree may die if the feeding is left unchecked.
If there are just a few bags on a tree or shrub, they can be picked off and thrown away. Do not throw them on the ground as the larva will climb right back into the tree and start feeding again. Insect control sprays work better on the younger larvae.
For more information about bagworms and ways to control them, contact your local Spring-Green professional.