Bagworms

Facts, Identification, & Control

Scientific Name

Thyridopteryx ephemeraeformis

Appearance

What Do They Look Like?
  • Color: Full-grown larvae are grayish in color.
  • Body: Adult males have wings, but adult females are worm-like and do not have legs or wings. Adults are about an inch long.
  • Characteristics: Bagworms are also referred to as evergreen bagworms. These insects have bags that are about one to two inches long and will increase in size as the bagworm larval stage grows.

How Did I Get Bagworms?

Bagworm moths make their homes in many types of trees, especially cedar trees. Larvae crawl to nearby plants and their bags can be seen hanging on trees that they feed on. Some may spin a silk thread that catches the wind and carries them off to new trees.

How Serious Are Bagworms?

Bagworm larvae grow and feed on trees causing plant damage. These pests can be dangerous and costly to landscaping plants, but they pose no threat to human health. Large infestations of these pests may damage or cause trees and shrubs to die from defoliation. These pests are likely to be a greater problem in urban environments where their host plants are commonly planted together.

Signs of Infestation

Egg sacs hanging from trees or plant defoliation can be signs of bagworms. These infestations generally go undetected until major plant defoliation occurs or a large number of bags become noticeable.

How do I Get Rid of Bagworms?

What You Can Do

Inspecting plants for the presence of either old or new bags is the first step toward prevention and control of this defoliating pest. Be thorough when inspecting since the plant’s dense foliage may hide some or all of the bags.

Inspection can be done at anytime of the year, but the best times are the late fall or winter before bagworm eggs hatch and larvae begin to feed and disperse.

What Orkin Does

Your local Orkin technician is trained to help manage bagworms and similar pests. Since every building or home is different, your Orkin technician will design a unique program for your situation.

Orkin can provide the right solution to keep bagworms in their place.


Behavior, Diet, & Habits

Since female bagworm moths cannot fly, larvae are responsible for infesting other trees as they move from one host tree to another, or if they are introduced via infested nursery plants.

What Do They Eat?

These pests feed on plant needles or leaves from different types of trees including:

  • Arborvitae
  • Cedar
  • Deciduous
  • Juniper
  • Pine
  • Spruce
Where Do They Live?

Bagworms may live in places such as:

  • Tree trunk
  • Limbs
  • Foliage

Life Cycle

Bagworms complete their life cycle by going through four stages:

Eggs

The eggs are deposited inside the female’s bag where they will overwinter. A female lays anywhere from 300 to 1,000 eggs inside the bag, and subsequently dies. In the spring, the eggs hatch from silk thread and each larva begins to construct its own case with tree foliage, where it will live throughout its larval and pupal stages.

Larvae

The larvae will enlarge the case as it grows and moves about by partially emerging its head and legs to feed and move to other locations. Being more or less immobile, female bagworms never leave the bag they built while they are immature larvae.

Pupae

The insect enters the pupae stage once the larval stage is complete. They stay in the bag until they are adults.

Adults

About one month later, the adult male moth will emerge and fly to the female’s bag where mating occurs.