Over the last few weeks I have received several calls about little brown balls or bags hanging from the branches of Leyland cypress, juniper, and arborvitae in our area. Sometimes these bags are even found on the sides of homes or on yard furniture as well.
These little brown balls or bags are actually the protective casings for an insect known as the bagworm. The bagworm is a common ornamental pest of the aforementioned species, but can also be hosted by practically any other evergreen or deciduous plant species.
The brown “bags” that are found in the trees are a telltale sign of bagworm activity. The bags serve as a protective structure for bagworm eggs. In the fall, female bagworms lay their eggs in the casings just before they die. The eggs hatch sometime in May and June of the following year, and the newly hatched bagworms leave the protective casings via silk strands similar to spider silk. These silk strands are light enough to be caught by the wind, and therefore allow for the bagworms to be blown into other susceptible trees nearby. Once on a suitable host, the bagworm spins a new bag.
It is during this time of year (August and September) that bagworms pupate out of their bags as moths and mating occurs. As stated earlier, this is the time of year when eggs are deposited in the bags. If left uncontrolled bagworm populations can become severe enough to kill even larger deciduous trees.
The easiest and most economical means of controlling bagworms is to just simply pinch or cut off any bags that are seen on the infested tree or plant. This can be done at any time of year. Once removed from the tree, the bags should be destroyed. This helps to break the life cycle of the bagworm population. Insecticide sprays can be used, but must be applied at the proper time. Bagworms casings act as protective structures that prevent bagworms from receiving contact with the insecticide. Sprays during the fall are therefore not recommended. The best time for an insecticide spray would be in June when the bagworms leave their protective bags and search out a new location. Orthene and Dipel are two brand name products readily available for homeowner use on bagworms.
Disclaimer: Recommendations for the use of chemicals are included in this article as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this article does not imply endorsement by North Carolina Cooperative Extension nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Read and follow all label directions when using any pesticide.
The following link provides more information on bagworms and their control: https://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/ort081e/ort081e.htm
For more information about bagworms or any other ornamental pest, please do not hesitate to give me a call at (910) 640.6606 or send me an e-mail at firstname.lastname@example.org