Bag Worms – Just Hanging Around

— Written By and last updated by

Bagworms are common insect pests found on many ornamental plants found in your yard. They have many plants that they will feed on but prefer conifers such as Leyland cypress, juniper, arborvitae and cedar. June and July is when you start seeing the small bags, that look like upside down ice cream cones. Bagworms have been known to completely defoliate plants. Once you have a serious infestation it is very difficult to eliminate them. Sometimes you even have to remove the plant. It is important to look for them and control them early to prevent major damage to plants in your home landscape.

Life Cycle

In June to mid-July look for small cone shaped bags hanging from leaves or branches. During that time newly hatching larvae will find a place on the plant and begin building their bag. They stick out their head to feed on leaves. Over the summer the bags will increase in size as the larvae grows. The larger they become, the more they can eat. Feeding stops once they go into the pupal stage. During August and September, the male moth emerges. The female bagworm moth stays in the bag and will lay between 500 and 1000 eggs in the bag before she dies in the fall. In the spring, the cycle starts again. Eggs hatch, larvae move within same plant or another one nearby and so forth.

Damage

Larvae stick their head out of the bag out to feed. First they eat the tips of the leaves, but as they grow, older larvae consume entire leaves. With a large population, plants can be completely stripped of leaves. The problem often is damage isn’t noticeable until late in the summer when the caterpillars are large and consuming a lot of leaves. Another problem is bagworms also attach their bag to the branch with a silken thread. It is often so tight, that it will girdle or choke that branch causing it to die.

Control

Hand picking the bags is often the best measure for control. Be sure to completely submerge the bags in soapy water to kill the insect and its eggs. If hand picking is not an option due to the large number of bagworms, several chemical controls are available.

During June and early July, either Bacillus thuringiensis (commonly called Dipel), bifenthrin (Onyx), azadirachtin (Azatan) or spinosad (Conserve) can be applied to the plants. Be sure to read and follow all label directions.

For more information or questions about your home garden, lawn or plants contact Shannon Newton, Extension Area Horticultural Agent, by phone at 910-875-3461 or by e-mail at shannon_newton@ncsu.edu.

Disclaimer: The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by North Carolina State University nor discrimination against similar products or services not mentioned.

North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran status or disability. In addition, the two Universities welcome all persons without regard to sexual orientation. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

Written By

Photo of Shannon NewtonShannon NewtonArea Agent, Agriculture - Horticulture (910) 875-3461 (Office) shannon_newton@ncsu.eduHoke County, North Carolina
Posted on Sep 8, 2016
Was the information on this page helpful? Yes check No close
Scannable QR Code to Access Electronic Version This page can also be accessed from: go.ncsu.edu/readext?425049