Best Insecticide For Bagworms



The sight of your trees being eaten alive can be devastating.

What are those ugly looking bags hanging off them?

Pulling them off and stamping on them is a natural reaction, but you’ll need an insecticide to kill the insect inside – the hungry bagworms.

Here are a few of our top choices for the Best Insecticide For Bagworms to get rid of them:


 How to tell if your trees are infested with bagworms

What to look for 

Occasionally, the evergreen trees display browning leaves or needles falling from their branches. Rather, they look sad and saddened.

In the summer, a large number of bagworms can cause the defoliation and death of evergreen trees. Broadleaf trees survive better since their leaves die in the fall and regrow in the spring. Almost any tree will do – pine trees, fruit trees, ornamental trees, shrubs, and perennial flowers. 


How to Tell if Your Tree Has Bagworms

More about the bagworms in trees

Bag worms are found in three types in North America:

There are three types of bagworms: the evergreen bagworm, the snailcase bagworm, and the grass bagworm.

There are both snailcase and grass bagworms that hang from fences and sheds – and the snailcase reproduces pathogenically without the help of males. In most cases, however, you will see the evergreen bagworm damaging your trees and shrubs.

The bagworm lives most of its life inside a bag, protected from predators like birds.


Large Bagworm Nest in a Walnut Tree
If bagworms are left long enough, you may find a nest like this in your tree.The bagworm eggs rest in old spindle-shaped bags during the winter. The bags are well camouflaged, made of silk threads with leaves embedded – you may not notice them unless you look very closely. They can even be mistaken for old pinecones on evergreen trees.Early in June, the eggs hatch – and then the damage begins. Larvae emerge from the bag and spin silk strands. The larvae may be blown to nearby plants by the wind. The larva spins a new bag around its body after finding a place to stay – and there she stays for the rest of her life.They are brown caterpillars at this stage. Feeding continues until late August, when they withdraw into their bags when threatened.

The bagworms begin pupating in August and emerge as small, furry grey moths in September. After mating, the males die, and the female lays her eggs (up to 500 in total) in the bag where she too dies, her body a mummy around her eggs.

Watch this video from the UNL Extension in Lancaster County – it has some clear pictures.


The plaster bagworm

Plaster bagworms are usually found in warm houses near spider webs (which they eat). A thorough vacuuming is the most effective way to remove bagworms from your house. You don’t want a party of well-fed moths living on your vacuum cleaner! Throw the vacuum bag in the trash and take it outside.


When to spray for bagworms?

Bagworms may be reduced by simply removing the bags by hand, crushing them, or drowning them in soapy water. You shouldn’t just throw the bagworms on the ground as they may climb up to their host plant. Do this in early May in conjunction with insecticide control.

In case you decide to treat by treating the ground around the tree, you should do that in May, because you want the young bagworm larvae to eat the leaves with the insecticide on them before they grow – when they are harder to kill.

Bagworms should be sprayed in late June or early July. The caterpillars’ appetites fall off if you wait any longer, they eat less, and your sprays are less effective. It is expensive to spray trees, and to kill bagworms you need to spray the wound hole tree thoroughly. When the bags have reached about 2 inches in length, the insecticides are no longer effective.


How to control bagworms

It is possible to crush or drown bagworms by picking them off by hand.

June and July are the best months to apply insecticide.

Bagworms are best controlled with insecticides such as spinosad, sevin, or malathion. These should be applied while the bagworms are feeding.

Early May, apply insecticide around the base of the tree. As the insecticide travels up the tree into the leaves, the bagworm eats them and dies. This is most effective on young trees and young bagworms.


What to look for in an insecticide

  • Safety 

In your opinion, what is most important when searching for a treatment? Keeping you, your kids, and your pets safe is our number one priority

  • A consideration of utmost importance is the safety of pollinating insects, like bees. The insecticides are often very powerful and can be extremely toxic, especially for aquatic life.
  • The method is effective. It needs to be a bagworm killer – and the way you spray or apply it affects its effectiveness – the time of day and the month of the year have an impact on the insecticide.
  • Do you have any trouble using it properly? Is it easy to use? Finding the right mix is essential.
  • Does the effect last for a long time?
  • Is protective gear necessary?
  • What is its ecological impact?
  • Can it damage my trees?
  • When should I apply the bagworm pesticide? Have I already missed the window?
  • Is it OMRI listed?

General advice

  • When it comes to killing bagworms, timing is everything. Spritz in June and July. If you cannot see the caterpillars and they are not feeding, and if the bags are not moving, then you are too late!
  • By picking off the bags by hand and drowning the worms in soapy water in April, you can reduce the number of bagworms.
  • Consider the ecological effects of the insecticide you choose


Reviews of Insecticide for Bagworms

Monterey LG6332 Bacillus Thuringiensis (B.t.) Worm & Caterpillar Killer Insecticide/Pesticide Treatment Concentrate

An insecticide specifically designed to kill worm type insects (including bagworms)

Monterey LG6332 Bacillus Thuringiensis (B.t.) Worm & Caterpillar Killer Insecticide/Pesticide Treatment Concentrate, 16 oz

Bacillus Thuringiensis can be used on a variety of plants, including edible vegetables. It is also safe for earthworms, ladybirds, and bees, all of which are beneficial to your garden provided you follow the instructions. 

Organic Materials Resources (OMRI) has approved it for organic gardening.

You can mix the insecticide with water to get the desired strength of the spray. Spraying the tops and undersides of leaves is extremely important – and a heavy infestation requires repeat sprays.

In order for the insecticide to be effective, the caterpillar must eat it. After they have eaten, they cease to feed – although you may not see any difference for several days. The best time to treat them is when they are small, because larger worms need more treatment and are harder to treat. The more they grow closer to pupating, the less active they are, so they need to feed constantly.

You can eat from the plant immediately after the spray, but don’t wash it off as the bagworms will only die if they consume it.



  • Safe
  • Easy to apply


  • Sunlight sensitive
  • Slow to see the effect

Check Amazon For The Latest Price

Ortho Insect Killer Tree & Shrub Concentrate

 Effective bagworm pesticide for heavy infestations of bagworms

Ortho Insect Killer Tree & Shrub Concentrate, 16 oz.A powerful bagworm killer, this insecticide is also effective against many other insect pests.

This product is recommended for use on ornamental shrubs and fruit trees. Spinosad, a fermentation-derived insecticide, is the active ingredient. You mix the concentrate with water and the bagworms begin to die off within a few days of application.

Pests are killed by the same dilution.

Since one dilution rate is effective for all pests, determining the right mix is easy. One pint is sufficient to treat over 2,500 square feet.

The company states that pets and children are safe if they follow the instructions on the label.



  • Controls many insect pests
  • One pint treats over 2,500 square ft
  • For residential use on fruits, nuts, citrus, and ornamentals
  • Only a single dilution rate needed


  • Effects are not immediately obvious

Check Amazon For The Latest Price

Fertilome Spinsosad Bagworm, Tent Caterpillar and Chewing Insect Control, RTS, Quart

 A user-friendly OMRI listed bagworm spray that is effective

Fertilome 40693 Natural Guard Spinosad Bagworm, Tent Caterpillar & Chewing (32 oz. RTS Hose End) Insect ControlSpinosad bagworm killer is OMRI-listed for use on shrubs, ornamental trees, lawns, and flowers. It contains 0.5% Spinosad, the active ingredient. Fertilome Spinosad is classified as an organic compound. 

It is user-friendly. It comes ready to spray, so there is no guesswork involved.

The insecticide has little effect on beneficial insects or predatory spiders, but does kill bagworms. Please note, you may still see bagworms on the tree/plants after the spray, but they will no longer be feeding and will eventually die off.

In addition, the company states that bees and children are not affected after three hours after using the product if you follow the instructions.



  • Child and pet safe
  • Bees safe after 3 hours
  • Easy application-ready to spray


  • Fast results not immediately obvious

Check Amazon For The Latest Price

Talstar Pro 96oz Insecticide

Talstar insecticide is effective at low concentrations

Talstar Pro 3/4 Gal | Multi Use InsecticideThis insecticide is a concentrate and contains 7.9% Bifenthrin – a powerful bug killer. Bagworm spray can be used on many plants and shrubs, as well as on lawns and buildings.

It is an odorless pesticide.

You need to dilute the concentrate with water according to the instructions on the label, and you should spray it when the larvae are very young and beginning to hatch.

By interfering with the bagworm’s nervous system, this insecticide eventually kills it, but it is not instantaneous. A good spray will control the bagworm population for up to three months, however.



  • Effective
  • Kills many insects
  • Can make a good barrier
  • Lasts up to to 3 months


  • Ineffective if frozen
  • No immediate effect

Check Amazon For The Latest Price

Bayer Tempo Insecticide Concentrate (SC Ultra)

Fast knockdown, lasting up to 4 weeks

Bayer Tempo Insecticide ConcentrateOther insects are killed by this powerful insecticide as well – and it works quickly.

Bagworms will be killed by it until they start making new bags (once this happens, insecticides won’t work).

The company states that SC Ultra can be used around children and pets once it is completely dried.

However, it is a powerful insecticide and you need to use caution when applying it. It can be absorbed through your skin, irritate your eyes, and should be applied with a user-friendly applicator to avoid inhalation. Wash your hands thoroughly after use.

ß- Cyfluthrin 11% was previously available only to professionals, but is now available for general use. In addition to being extremely toxic to aquatic life, it should not be allowed to run off. It should not be used in greenhouses or nurseries.

If possible, spray the underside of leaves as well, and use it at dawn and dusk, when pollinating insects such as bees are less likely to be present. Spreader-stickers can be added for leaves that are difficult to cover, such as evergreen pine needles.



  • Fast-acting
  • Safe after drying
  • Effective
  • Odorless


  • Toxic
  • Need precautions

Check Amazon For The Latest Price


For us, the outright winner has to be Monterey LG6332 Bacillus Thuringiensis. The bacillus Thuringiensis is targeted at bagworms, and valuable earthworms and insects such as the pollinating bees are unaffected. An important factor for us due to the declining bee population.

Monterey LG6332 Bacillus Thuringiensis (B.t.) Worm & Caterpillar Killer Insecticide/Pesticide Treatment Concentrate, 16 oz

Monterey LG6332 Bacillus Thuringiensis (B.t.) Worm & Caterpillar Killer Insecticide/Pesticide Treatment Concentrate, 16 oz

    • This pest control is designed to kill caterpillars and worms, such as cabbage loopers, bagworms, gypsy moths, fall cankerworms, elm spanworms, and more.
    • This insecticide is designed for use on a wide variety of plants including broccoli, celery, cabbage, turnips, mustard greens, cauliflower, melons, lettuce, tomatoes, shade trees, ornamentals, and many more.
    • Monterey B.T. is safe for earthworms and bees when used as directed. It does not affect birds, earthworms, bees, ladybugs, or beneficial insects.
    • For organic gardening, our insecticides are listed and approved by OMRI. OMRI, the Organic Materials Review Institute, determines if a product qualifies for the USDA’s national organic program.
    • The product instantly mixes with water and can be applied with either a trigger spray bottle or pressure tank sprayer. Always read and follow the instructions on the label.


    Check for Latest Price

    In case of a heavy infestation, you may wish to use a really powerful bagworm insecticide such as the Ortho Insect Killer Tree & Shrub Concentrate, and provided you carefully follow instructions, this should be safe for your children and pets once completely dry.

Leave a Reply

Your email address will not be published.