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Bagworm Control- Comprehensive Guide on How To Get Rid Of Bagworms

Summer often brings a plethora of fun outdoor activities and events, but it also brings the warmth and moisture that Bagworms can thrive in.

This creates the need for Bagworm Control for many homeowners who struggle in knowing how to get rid of bagworms.

Along with the emerald ash borer, bagworms are some of the most annoying pests for the beautiful lawn, trees, and landscape you’ve built and cared for! At Ryan Lawn & Tree, we’re always on the lookout for anything that can destroy your sacred outdoor living space — whether you’re in Tulsa, St. Louis, Wichita, Kansas City, or Springfield — so we’re offering this quick rundown on how to properly get rid of bagworms as well as common FAQs about them.

What Are Bagworms?

Bagworm Control Guide

Bagworms are often seen on evergreens inside their hanging bag.

You may only think of bagworms as those long, thin, brown sacks they create of silk in the fall and you see hanging from your favorite evergreen. However, this seemingly innocent silk holds up to 1000 eggs which hatch in the late spring or early summer and then feed on your beautiful green branches, making proper bagworm control necessary.

At Ryan Lawn & Tree’s Midwest locations, the most common targets for bagworms are eastern red cedar, junipers, and arborvitae. Bagworms also sometimes damage pines, spruce, bald cypress, maple, box elder, sycamore, willow, black locust, oaks, and roses.

How To Get Rid Of Bagworms

The easiest way to get rid of bagworms is to cut off the bags by hand and destroy them. Lift branches, clip off bagworm egg sacks, and drop them into the bucket of water with dish soap, making sure they are submerged fully. Dump the soaked bagworms into a sealed plastic bag and throw them in your trash. Repeat this procedure every fall, winter, and early spring to reduce bagworm populations before the eggs hatch. If this process doesn’t appeal to you, or your bagworm population is overwhelming, turn to your certified arborists at Ryan Lawn & Tree for help!

Life-Cycle Of A Bagworm 

The life cycle of a bagworm has four stages — the egg, larvae, pupal, and adult.

  1. Bagworm Eggs — The overwintered eggs (in the year-old female bags) begin to hatch in late April or early May.
  2. Bagworm Larvae — Young larvae (caterpillars) begin to feed and construct bags immediately. As the larvae grow, they add to the bag until it’s at its full size — around 2” long. They use the silk to fasten the bag to a tree step.
  3. Bagworm Pupal — In August, pupation occurs inside the bag.
  4. Bagworm Adult — In late August and September, the adult males emerge as bagworm moths and search for wingless females still inside their bags for mating. After mating, the female lays several hundred white eggs inside her old pupal case, drops from the bag, and dies.

What Does A Bagworm Look Like?

  • Bag — The 2” brown, cocoon-shaped bag is the most visible evidence of bagworm infestation but once hatched, the bagworm makes several transformations. The “bag” of the bagworm is created from their silk and pieces of tree and then eventually filled with eggs.
  • Larvae — Larvae emerge as tiny black dots about the size of a pinhead, and light as a feather. These caterpillars can use their silk to “fly” to other trees and build new homes. Once full-grown, the 1” long larvae have a dark brown abdomen and the head and thorax are white, spotted with black.
  • Adults — The adults are small moths with clear 1” wings and a black, hairy body. Male bagworms are ashy-black. The adult female’s body is soft, yellowish-white, and practically naked except for a circle of woolly hairs at the posterior end of the abdomen. They are wingless and have no functional legs, eyes, or antennae.

What Damage Do Bagworms Cause?

Bagworms prefer evergreens, like juniper, arborvitae, cedar, and spruce, but will attack more than 128 different types of trees and evergreens. Bagworms in their larvae stage do most of the damage as the caterpillars feed on buds, needles, and plant material while creating their bags causing branch tips to turn brown and then die. In heavy infestations, bagworms may eat more than 80 percent of the tree, killing an entire evergreen. On deciduous trees (those that lose their leaves in winter), bagworms chew small holes in the leaves that can cause defoliation. Without bagworm control, these trees may survive, but in a weakened state that leaves them more susceptible to the emerald ash borer and diseases.

What Do Bagworms Eat?

Bagworm larvae eat the most and therefore cause the most damage. As caterpillars, bagworms feed on evergreen needles and the leaves of deciduous trees. If your trees are infested with bagworms, you may notice that they leave only the largest veins of leaves behind. Bagworm larvae tend to only emerge from their bags to eat and return to rest or hide in the sight of danger.

Bagworms eat over 100 different types of trees, although they prefer evergreens such as:

  • Red cedar
  • Juniper
  • Arborvitae
  • Spruce

Other common victims of the bagworm include:

  • Pine
  • Bald cypress
  • Maple
  • Boxelder
  • Sycamore
  • Willow
  • Black locust
  • Oaks
  • Roses

What Do Bagworms Turn Into?

When you think of bagworms, you probably imagine the larvae, wingless creatures that live inside silken brown bags and emerge to feed. These caterpillars pupate inside their bags around August. Once fully grown, male bagworms emerge as adult moths. They have small, dark, hairy bodies and clear wings. The female adult bagworms are wingless and have no legs, eyes, or antennae. Their bodies are soft and lightly colored. The females most resemble a “bag worm” and simply wait for a male to come along and fertilize their eggs. Once he does, she lays between 300-1000 eggs in her old bag and dies. 

When To Spray For Bagworms?

The best time to spray for bagworms is when larvae are feeding vigorously. This may change depending on your location and the season, but it is generally after early May and before early July. In August, bagworms begin to eat less (which means they will consume less insecticide) as they prepare to pupate into adults.

If the larvae have already stopped feeding, you should wait to spray for bagworms until next season

What Causes Bagworms?

In short, other bagworms cause more bagworms. A single bagworm egg sack (or bag) can contain between 300-1000 individual eggs. Once hatched, the larvae resemble tiny black dots and grow into larger caterpillars. At an early age, the larvae spread out, “flying” onto other trees from their original nest by using silk threads. Then, they create their own bag out of the same silk and plant material from the host tree. Once they turn into adults, female bagworms lay their eggs in the sack they grew up in, and the cycle begins again.

How To Prevent Bagworms?

Using insecticide on the affected trees when young larvae would be feeding is the most effective method to prevent bagworms. Some of the most common products on the market to prevent bagworms include carbaryl, malathion, diazinon, bifenthrin, permethrin, or cyfluthrin. Before applying products, always read all instructions and warnings, and be sure to take into account the stage of plant development, soil type and condition, temperature, moisture, and wind.

For a natural treatment, you can also use products containing Bacillus thuringiensis var. kurstaki, a naturally occurring bacteria in soil that causes bagworms to stop eating and die in a few short days.

You can also prevent bagworms by attracting their natural enemies, such as birds and wasps. Placing Shasta daisies, Frikart’s asters, birdbaths, birdfeeders, and bird feeders near bagworm trees will help you prevent and control bagworm populations.

If you already have bagworms, the best method is to hand cut the bags, kill them, and throw them away.


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