Controlling Bagworms on Your Evergreen Trees and Shrubs.

Bagworm Background

Evergreen Bagworms (Thyridopteryx ephemeraeformis) are a common pest found along the Eastern half of the United States, from the Atlantic Coast to Nebraska, as far North as Maine, and as far South as the Gulf of Mexico. Bagworms prefer Arborvitae and Cedar, but can also be found on Juniper, Pine and Spruce; as well as deciduous trees such as Maple, Oak and Birch.

With an incredible appetite, bagworms are a serious threat to the prolonged health of your landscape that can wreak havoc on your property's evergreen trees and shrubs. Female bagworms can lay hundreds of eggs per year, resulting in huge population increases in a short amount of time. This rapid population growth can lead to severe defoliation of host plants and their neighbors, which can cause plant death and large, unsightly dead patches in the plant.

Bagworm Control

Controlling bagworms on your property can be accomplished through manual removal of the bag, through the application of insecticdes such as Sevin, and through biological control with bacterial spray. Manual removal is time intensive and is easiest after mid summer, when the bags turn brown and are easiest to spot. After picking bagworms from the plant, the bag can either be manually crushed or double-bagged in trash can liners and disposed of in the garbage.

The use of insecticide and bacterial sprays is much more efficient than hand-picking, but requires the application to take place at the correct time, when bagworm larvae are feeding on the plant. Bacterial Spray Bt (Bacillus thuringiensis) and insecticde should be applied using two timed applications. The first application should be made in early to mid-June, with the second application being made in late June to early July. This double application allows for some redundancy in case the Bacterial Spray or insecticide is washed off by rain and ensures that all larvae are exposed to the applied bacteria or insecticide . It is also important to note that complete coverage of the plant material with insecticide or Bacterial Spray is vital to ensure effective control, as the bagworm larvae will only be killed after ingesting the applied control measure.

Bottom Line

Bagworms can be a huge problem for property managers, resulting in costly plant removal and replacement if they are not controlled early. The good news is early control is easy and cost effective in the long term. If you have noticed a bagworm infestation on your property, or would like to have your evergreen trees and shrubs inspected for free, contact our team today. We'd be happy to come take a look at your landscape and provide you with pricing for either manual, bacterial, or chemical control of any bagworms on your commercial property. As always, our consultations are no-cost and no-obligation.


Shetlar, DJ. "Bagworm and its Control." Ohio State University Extension. The Ohio State University, 05 Oct. 2011. Web. 24 July 2017.

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