• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Texas A&M Forest Service
  • Texas A&M Veterinary Medical Diagnostics Laboratory
  • Texas A&M AgriLife Extension Service
  • Texas A&M AgriLife Research
  • Texas A&M College of Agrculture and Life Sciences
Hunt County Master Gardeners
Hunt County Master GardenersTexas A&M AgriLife Extension Service
  • Menu
  • Home
  • Articles
  • About
    • Who We Are
    • Program Overview
    • FAQ
    • Contact
    • Master Gardener Emeritus
    • Heritage Garden
      • Animal Name Bed
      • Heritage Garden Plant Database
    • Hunt County Master Gardeners Shutterfly Photos
    • Junior Master Gardener Program
    • Outdoor Learning Center
  • Events
  • Links
    • Hunt County Extension Office
    • Texas AgriLife Extension Bookstore
    • Aggie Horticulture
    • Aggie Turf
    • Texas Master Gardener
    • Texas Master Gardener Association
    • Texas Master Gardener License Plates
  • Resources
    • Plants for East Texas
    • Vegetable Resources
    • Fruit & Nut Resources
    • Texas Plant Disease Diagnostic Lab
    • Soil, Water and Forage Testing Lab
    • Texas Superstar Plants
    • Earth-Kind Landscaping
    • Xeriscape
    • Insects in the City
    • USDA Plant Hardiness Map
  • CEUs
    • Log My Hours
    • Texas Master Gardener Association Events
    • Master Gardener Advanced Training
    • Earthkind Online Classes
    • Landscape Design Study Courses
    • American Horticultural Society Events
    • Texas Botanical Gardens and Arboreta

The Bane of Bag Worms

April 5, 2014 by stephaniesuesansmith

The Bane of Bag Worms by Pat Newell

Although bag worms are not abundant every year, once a plant is infested it can become a persistent problem. If an infestation is left unchecked they can defoliate and kill trees and shrubs.        I learned an important lesson while researching this information. As an example of using individual’s sites for research, my initial search said that bagworms turn into web worms. When I went to several University Extension sites that turned out not to be true. Bagworms and webworms are two entirely different insects. Bagworms look like small shaggy Christmas ornaments, or tiny pinecones, about 2 inches long. Once you know what to look for they are easily visable in winter.  Normally they are in Evergreens, and Sweet Gum trees, but any plant may be susceptible, such as Oaks, Pecans, and fruit trees.

Eggs hatch in the bags in spring, the larvae, or caterpillars, then emerge, and fall to the ground. They then go back up into the plant where they eat leaves and make new bags, or enlarge the existing bags, as they grow. In September the caterpillar pupates, or turns in the moth. The winged males mate with the females, who then lay the eggs in the bag, dies, and the eggs over winter in the bags. If this cycle can be interrupted at any stage the problem disappears.

Interrupting the cycle, however, may be easier said than done. If the bags are in small, or short, plants, hand picking the bags is the most reliable treatment. You will notice as silken thread that holds the bag to the tree. If possible remove the thread as well, since it can choke the twig it is on.  It is important not to throw the bags on the ground, since this does not interrupt the cycle. The larvae can hatch on the ground as easily as on the tree. Placing them into a ziplock bag, sealing it and putting it in the trash is the best method of disposal. Unfortunately many of the trees have bags that are too high to reach, even with a rake to pull down the branch. If the tree is badly infested, and is worth the cost, professionals can be brought in the handle the problem.

Since a professional spraying into a 40 foot tree is beyond the means of many of us, several other methods have been suggested in various University Extension sites. The most important thing about treatment, even before knowing what to do, is timing it to be most effective. If you are able to reach any of the bags, put them in a dark place. I use a can with a good lid. In spring open the can frequently so that the larvae can be seen as they hatch. This is the best time to treat the caterpillar problem, while the larvae are small and feeding. Various insecticides are recommended at this stage, the easiest being a soil application of Dinote Furan, or even the reliable Seven dust around the base of the tree. Since the caterpillar has to climb back up the tree to feed, one very respected Extension site even recommended a bird feeder near the base of the tree, or spreading seed around the base of the tree for ground feeding birds.

The Fall, while the bags are still small, is the best time to use the various sprays that can penetrate the still thin walled bag. BTK, Malathion, Neem oil, Spectracide Bug Stop have been proven to do the job.

Seeing all those bags hanging can look like a problem that can’t be controlled, but timing, insecticides, and even some old time basics can get rid of the shaggy, deadly, Christmas ornament looking bags that can destroy our trees.

Filed Under: Entomology Tagged With: Bag Worms,

Find Us on Facebook logo

Articles by Topic:

  • Composting
  • Earth-Kind
  • Entomology
  • Events
  • Flowers
  • Fruits and Nuts
  • Gardening 101
  • Herbs
  • History
  • Keyhole Gardens
  • Ornamentals
  • Plant Diseases
  • Recipes
  • Roses
  • Seeds
  • Square Foot Gardening
  • Trees
  • Turf
  • Vegetables
  • Water Conservation
  • Wildlife
  • Winter

Article Key Words

African Violets Asparagus Bag Worms, Bees Birds, Bluebonnets, Brown Patch, Butterflies, Composting Dragonflies eGardening with the Master Gardeners, Fall Tomatoes, Fire Ants, Fruit Trees Garlic, Gifts, Grapes, Grasshoppers, Greenhouses, Keyhole Gardens Late Fall Vegetables, Late Spring Gardening, Leeks Notable Texas Gardens, Onions, Poison Ivy, Poisonous Plants, Potatoes Propagation Pruning Trees, Rainwater Harvesting, Raised Beds Rose Hips Spider Mites, Spring Vegetable Gardening Squash Bugs, Summer Trees & Shrubs, Turf Grass, Valentines, Vegetables Watering Water Wise Gardening, Wildflowers, Winter
Texas A&M AgriLife Extension Service
Texas A&M University System Member
  • Compact with Texans
  • Privacy and Security
  • Accessibility Policy
  • State Link Policy
  • Statewide Search
  • Veterans Benefits
  • Military Families
  • Risk, Fraud & Misconduct Hotline
  • Texas Homeland Security
  • Texas Veterans Portal
  • Equal Opportunity
  • Open Records/Public Information