What is a Bagworm?

It is a perennial moth like insect that is wingless and resides on a number of evergreen as well as junipers. It causes extensive damage to plants and trees.

Scientific Classification

Thyridopteryx ephemeraeformis

Table Of Content

Scientific Classification

Thyridopteryx ephemeraeformis

Other names for this pest are Common Bagworm and Evergreen Bagworm.

What is a Bagworm like?

Adult males of this species of moths are dark and hairy in appearance with a wingspan of approximately 1 inch. Female bagworms look like maggots and are yellow in color. An average insect of this type appears similar to a tiny caterpillar.

Picture of Bagworms

Picture 1 – Bagworms
Source –

These pests are about 1-2 inch in size.

Family Name

This pest is a member of the family Psychidae and belongs to order Lepidoptera.

What does a Bagworm eat?

Bagworm food comprises of leaves of plants. They are parasitic in nature and reside in plants, feeding on them. Bagworm larvae feed on leaves and needles of evergreen plants. Young insects of this species eat the upper epidermis of hosts, which leaves tiny holes on the foliage of these plants.


The pest generally resides and feeds on Willow, Sycamore, Spruce, Maple, Bald Cypress, Boxelder, Oaks, Rose Plants, Black Locusts, Pines and other deciduous trees. It also attacks fruit trees, ornamental trees, perennial flowers and decorative shrubs.

Life Cycle

Bagworms life cycle are differentiated into separate stages, much like any other organism. Here is a glimpse into the various Bagworm life stages –

  • The eggs of Bagworm moths hatch in end of May and beginning of June. Once the eggs hatch, the larva spins a silk strand that hangs down it. The larva is also transported to nearby plants by wind.
  • Once the larva finds a host, it starts to make a new protective bag around itself. It remains inside this bag sticking only its head out to eat from the host.
  • The larva continues feeding until it matures by the end of August. It then attaches the bag they are in to a branch with a strand of silk and starts developing into a pupa.
  • Adult male worms appear in September. These are tiny, grayish moth-like insects with fur on their body and transparent wings. Adult Bagworm females are wingless. They never leave the protective bag.
  • When fully mature, these pests mate and die immediately afterwards.


Mature male and female worms mate with each other to produce offspring. Strikingly, these pests die after mating. Male moths die outside the bag after copulation. Females die inside the bag and get mummified around the mass of several hundred eggs that they produce. The eggs hatch in end-May or beginning of June.

Only one generation of Bagworm eggs are produced every year.


These pests cause excessive damage to plants. Only deciduous plants can withstand the onslaught of these plants. In Deciduous plants new leaves arise every year. This is why the defoliation (loss of foliage) caused by the parasitic feeding of this insect does not kill these plants. All other plants are incapable of surviving Bagworm attacks. The worm is controlled with insecticides because of this reason.

For control of Bagworms insecticides should be sprayed on young larvae during late- June or early-July.  This is the best time to apply insecticides for Bagworm control as feeding by these moths slow down by August. Naturally, chemical control during this time is not as effective.

Common insecticides used for controlling this pest include Carbaryl, Acephate, Cyfluthrin, Permethrin and Malathion. Affected plants must be thoroughly sprayed with any of these pesticides in June for Bagworm killing as soon as they start feeding on plants.

Moth Bag

Bagworm Bags Pictures
Photo 2 – Bagworm’s Bag Image
Source –

Protective bags of these insects hang from slender stems of plants and trees and are generally hidden by foliage. These Bagworm nests are usually brow or gray in color and look like small pine cones. Once spotted, these should be immediately cut away with garden shears, scissors or knife. Simply pulling away these bags will leave a silk strand behind that will encircle the twig while it is growing.

Organic Control

An organic pesticide that contains the bacteria Bacillus Thuringiensis is often used on plants in early spring for controlling these moths. The chemical is safe to use in plants in areas where pets and children roam about. There are many other chemical sprays available to control these pests.


The insect can be managed by both chemical and non-chemical means. Chemical process of getting rid of Bagworms involves spraying insecticides and organic pesticides on the habitats of the pests. Non-chemical way of Bagworm removal includes cutting away the bags formed by these worms from plants they have infested. Bag removal should be carried out in early spring, late autumn or winter season before the eggs hatch. Proper disposal of these bags will help avoid return of these insects.

Are Bagworms Poisonous?

Bagworms are often mistaken to be poisonous creatures as they cause the death of plants. This is however, a non-poisonous bug that causes plant death due to feeding on their foliage. Insecticides used for Bagworm prevention often produce toxic effects when used in large quantities. Safety precautions and usage directions on labels of pesticides should be strictly followed to avoid damage to valuable plants. When used in excess, these can not only damage plants but also contaminate ponds or streams located nearby.


Ichneumonid wasps and parasitoid insects are two organisms that are natural enemies of this pest.

Natural Control

These pests can be naturally removed in two ways. Manually removing the nests of these bugs is one such option. It can also be controlled by planting daisy plants near plants where the pest is found to nest on. Research conducted by the University of Illinois has shown that flowering plants such as daisies that are members of the Asteraceae family can attract parasitoid insects to them. Naturally, Bagworms nesting on such plants have a high chance of being destroyed by parasitoids.


Images of Bagworm
Picture 3 – Bagworm Picture
Source –

Want to get an idea about the appearance of this insect? Here are some Bagworm photos that you will find useful. Take a peek at these Bagworm images and know about the appearance of these pests.

6 responses to “Bagworms”

  1. Pichra says:

    I want to know about bag worms, especially when it outbreak.
    How do i need to solve the problem?

  2. Jean & Rick Byers says:

    Used Fantastik scrubbing bubbles with bleach 5 in one. We found that spraying the cacoons with this item made them drop to the ground and we raked them up and burned them. the spray did not hurt the tree and it worked great. Made them wiggle then dropped off whatever they were attached to.

  3. wood says:

    My extension agent in Central Virginia said to use the Bacillus T bactirum on them from May-June.. Then to use Seven on them from June – early July. After July he said only a professional treatment of Talstar Pro or Bifenthrim 7-9% strenght would get them out of that cocoon. If you have waited to late August to get rid of them he said its best to pick them and burn them using kerosene. He says you do Not want to have them a 2nd or 3rd generation as they WILL KILL your tree. My trees are 35 ft Blue Spruce trees and I am getting a professional with a bucket truck to get the bags off the top I cannot reach.But I did try spraying them. Used a Solo Backpack Sprayer

  4. Steph says:

    I’d like to see pictures of the larvae before it forms a bag. I’m not sure if what I’m seeing all over the ground under an infested cedar bush is larvae or something else. The bush is going to be removed next week. Does the ground need to be treated?

  5. Steph says:

    Maybe it’s not the larvae, but rather the eggs?

  6. Christine Williams says:

    Do they lay their eggs on the plant or around the base of the tree?

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