Big Bad Bag Worms and How to Kill Them

By Allyn Paul, filed under Environmental Info, Home & Lawn Insects, Landscape Tips.


Bag Worms are out in full force this year throughout the Midwest and beyond. I have been noticing more and more bag worm infestation in Indiana and Illinois in the last few years. Previously, I rarely say them north of mid-Ohio. This Landscape Tip is crucial (and funny) so read it thoroughly eh?

With this in mind, here is all the information you need to know about bag worms and how to either prevent or get rid of them in your landscape. I’m also going to let you in on the ‘darker side” of the bagworm lifestyle! It ain’t pretty!

There are three main types of bag worms in the United States:

  • Evergreen bagworm
  • Snailcase bagworm
  • Grass bagworm

Evergreen bagworms are the most common and are represented in the pictures here that I took at a golf course in St. John, Indiana. In reality, evergreen bag worms can be found in New England, all the way down to Texas but are more concentrated in the Midwest.

The Snailcase bagworm is found throughout the mid Atlantic but appears to be migrating towards the Pacific coast. Each type of bagworm creates a specific type of bag relative to its feeding habits. Most of the information here is about the evergreen bagworm.

BagWorm Life Cycle

Bagworms survive winter as eggs inside a tear-drop shaped bag found on a variety of trees and plants. The Evergreen Bagworm prefers evergreen trees and shrubs such as the blue spruce, arborvitae or cedar. There can be more than 800 eggs in each bag and they emerge as larvae in May. The larvae then use a combination of silken secretion and parts of the plant to create the bag around themselves. If you look closely at evergreen bagworm bags, they look very much like the plant leaves on which they infest. This larval stage is also when these little devils are eating and feeding on the plant; killing it!

In later summer and fall, when the bags are around two inches in length, the larvae suspend the bags pointing downward from twigs during which time they transform into the pupae or ‘resting stage’ before becoming adults. (adults are moths) Evergreen Bagworms’ bags look like small pinecones.

Bangin’ in the Bag

The male adult evergreen bagworm emerges in early fall as a moth, and flies around in search of females who are still in their bags. (If this bag’s a rockin’…don’t you come-a-knockin!) The female will produce pheromones that attract the males to her bag (it’s like Channel #5 for insects… c’mere baby, check out my hot bag!) The male inserts his abdomen into a hole in the bottom of the bag to mate. (Oh geeze, this is getting PG-13 now!) The female then lays several hundred eggs in a sack and then drops from her bag and dies. (dat’s right ho!) The eggs remain in the bag until May of the following year when the process starts all over again. (But what about the dude?..is he over at the bar smoking a cigarette?) …Adult male bagworms as moths survive just long enough to mate, but due to underdeveloped mouthparts, they can’t eat, so they die. (I hate those weak mouthparts!)

The Baby Bag Drag

As young larvae (before they have a ‘big bag’), Evergreen Bagworms spin strands of silk that carry them from pant to plant where they feed. This is why you sometimes see a line of arborvitae dying out in a row from bagworm infestation. When threatened, larvae will scoot inside their bag and hold the opening closed. The larvae feed on needles on conifers (evergreens). They will drag that stinkin’ bag all over a plant, feeding along the way. Around the country, they damage: orange trees in Florida as well as junipers, spruce, pine, willow, apple, maple, elm, birch and cedar trees across the US.

If the infestation is concentrated, they can completely defoliate a small shrub in about 2 weeks. Leaf damage is usually noticeable in starting in June and worsening in August.

How to ‘bag’ the Bagworm (Killem’)

When infestations of bagworms are diagnosed early (like June), control is fairly easy. Once population numbers begin to multiply and spread to numerous locations, control will be tougher but still possible. If bagworm infestations are not noticed until late summer, not only will their numbers be higher but the bagworms will have grown enough to make them more difficult to kill with an insecticide. The thicker the bag, the tougher the kill!

The easiest way to reduce the largest population of bag worms is the actually “pick” the bags off your trees and burn them in your firepit! In addition, you can use a general purpose tree and shrub insecticide spray. THe best types of insect control for Bag WOrms on trees and shrubs will work “systemically” which means they are taken up the plants roots and protect from the inside out! Here is the very best produce I have found to get rid of bag worms and pretty much any other insects as well.

Bayer Tree & Shrub Insect Control Conc.
If you have an infestation of bag worms this year, I’d definitely recommend you treat your evergreens early next year starting in June, just in case you missed any of the previous year’s bags!

Don’t you feel dirty now? I sure do.


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39 Responses to “Big Bad Bag Worms and How to Kill Them”

  1. Lawn Moths, Sod Webworms, and How to Control or Eliminate Them | Life and Lawns Says:
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    [...] thing about Talstar is you can also use it on your trees and shrubs to kill Japanese Beetles and Bag Worms. It is a very versatile product that will kill any insect in your lawn and trees and shrubs [...]

  2. BigPappa Says:
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    Holy crap, good thing you told me what they were. I thought I was being invaded by the pod people or something.

  3. Donna Hahn Says:
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    How do I know if my 15 ft. Blue Sprucetree is too far gone? It just started looking like death this spring 09. All the shrubs circling it are also dying (globes) Most of the bottom branches are bare and needles are all over the ground.

  4. Allyn Paul Says:
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    if it is bagworms, then the damage would have started last year. could it be something else?

  5. Dale Says:
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    Regarding Bagworms on Blue Spruce,how soon does the systemic need to be put on the ground to be absorbed into the tree to be effective?I have used orthene and talstar in the past,and sprayed the bugs directly,but Ive also had issues with taking the Blue color right out of the tree. Systemics seem like the better way to go,but I dont know if its too late since I already see the miniature bagworms forming on the branches.

  6. Allyn Paul Says:
    4Avatars v0.3.1 v0.3.1

    you will have to read the label on what you purchase, but most systemics are up into the plant within a week or less. Bagworms feed all the way until the fall, so it is definitely NOT too late to hit them!

  7. Stacey Says:
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    I was horrified by what I saw last night. i noticed my tree was dying and looking closer, I saw it moving. Getting closer I saw the little DEVILS half way out of their sacks munching and crunching my poor little tree to death. These nasty little worms gave me nightmares. I have to say this is one of the most frighting this I have seen. The whole tree is covered and wiggling with bag worms. I wanted to set the whole tree on fire and kill them but my tree is right next to the house. Please help! Any advise will be appreciated. Can I get this product at my local Co-op or plant center? I need it ASAP. Thank you in advance.

  8. Allyn Paul Says:
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    go to home depot and get any general tree/shrub insecticide spray and kill em with that! If you order from Amazon, you will have it within a couple days.

  9. Melony Says:
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    One of my trees is covered with bag worms.Looks like it has spreaded to several others. I bought something from home depot to spray but I was told it may be too late if the worms are mature. I have about 20 arborvitae in my yard which would be costly to replace. Any help on what to do.

  10. Allyn Paul Says:
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    get the products I recommend here and use them according to directions on label. you should also pick the bags off and burn them in your fire pit if you have one. seriously, you MUST do this or you will lose these Arbs.

  11. vicki hansen Says:
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    Are the worms green and look exactly like the pine needle itself? I had the same nightmare with the wiggling tree. I sprayed them with seven. Dont Know if it will work, but I have huge trees also that I cant reach way up. I noticed the trees have something that looks like spit or something. Is that the same thing?

  12. Allyn Paul Says:
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    Hi Vicki,
    bag worms look like pine cones. if you see worms that look like pine needles, those are saw flies and are very serious as well but typically stop feeding this time of year. Sevin will do ok but will beed to be reapplied.

  13. vicki hansen Says:
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    what about that spit-looking substance? I notice it all over on lots of different kinds of evergreens and some bushes. There is a worm inside that substance. Is that the same thing?

  14. Dale Says:
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    Vicki,I dont know about SPIT, but are you talking about a WEB that has worms in it? They are very common and are either web worms,tent caterpillars,or Gypsy moth caterpillars.Any of these pests can be controlled with the Seven you are using,or Orthene, Talstar and a few other pesticides.

  15. J Allgeyer Says:
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    How do the worms move from tree to tree? We have two trees on either end of a row that are completely dead now and the trees in between have some bags on them. If we pick off the worms on the trees that are still alive will they make it?

  16. Allyn Paul Says:
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    The worms spin a silk substance that carries in the wind and pulls them from tree to tree or bush to bush. these guys really are a nightmare’

  17. vicki hansen Says:
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    no it is not a tent. I have seen those. Maybe a better way to explain, it looks like a wet soapy substance that sticks to the tree, almost all my evergreens, and I have alot. If i spray the ones I can reach with seven, the substance melts and drips off. The next day its gone. I am really frustrated cuz I dont know what Im dealing with. As it is Im losing my oaks to oak wilt, and now saw flies, and then this stuff I dont know what it is.

  18. Rick Says:
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    I thought they were little pine cones and thought it odd today I noticed the top of My Leyland Cypress was dying and the others were turning brown. Upon closer observation they were moving. Sprayed but I am picking worms tonight and having a little mashmallow roast.

  19. Dale Says:
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    I have found that the Bagworms in southern New Jersey are coming out late this year.Im only seeing them now that its mid July,which is about a month and a half later than past years.
    My question is whether anyone knows,when the Bagworms are sprayed with pesticide,if when they manage to miss getting sprayed by pulling into theyre cocoons,will they continue to eat and ingest the chemical that is on the tree(White Pine)and is that enough kill them?I was told you needed to make direct contact with the pest to kill them,but even though they are still really small,their protective nests are already developed.Rain was not expected for several days following spraying,so the residule spray would remain on the trees.2

  20. Beth Says:
    4Avatars v0.3.1 v0.3.1

    I have spent the last three nights picking bags!! About 8 hours total!! Last year we did this, saved the trees, but unfortunately only got half the story of how to kill the little buggers! Hopefully this year I have saved the trees again, and now armed with Talstar and the Bayer systemic you recommended I will not have to Pick worms again next year! I have 10 trees lining my yard and I am determined to win! I filled 3 plastic shopping bags completely full of the little munchers!! Fingers crossed I got enough of them off to save the trees! I will continue to spray til fall and then next spring and hopefully the systemic will kick in soon too! Thanks for the helpful info!

  21. Allyn Paul Says:
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    the spray is not designed to kill on contact. It is designed to kill them when they take a couple bites. That is why I rec the systemic control in addition to the spray of Talstar

  22. Thom Says:
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    Good God. I just noticed one of my little evergreens covered in these things. My daughter and I picked well over 100 of pods off the tree, which is just 5 ft tall. I then sprayed the tree down with a insecticide that claims to kill the suckers.

    Thanks for the ed. on this grub.

  23. Pam Cicero Says:
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    Early this summer I noticed that the ends of the stems on my evergreen tree had turned brown. Is this the first sign of bagworms?

  24. kap Says:
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    I’ve used wasp spray that sprays 20 feet. I’ve gotten rid of bag worms and the trees have survived.

  25. Ashley Says:
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    We are attempting to kill the bagworms on our trees. We noticed that trees surrounding our property have bagworms as well (very badly). If we kill the ones on our trees, will they just come back from the trees on the other property?

  26. Allyn Paul Says:
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    Hi Ashley,
    yes, they will continue to spread back into your landscape from neighboring ones. That is why I recommend the systemic product above. (the one that is taken into the plants through their roots) and you should plan to use that product each year as a protective/preventative measure for the bag worms. They are nasty little things for sure and they do MAJOR damage if left un-treated.
    Here it is again in case you missed it:
    Bayer Tree & Shrub Insect Control Conc.

  27. Dolores Martin Says:
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    Thanks for the wonderful information, however I don’t know what to do in my situation. I have a beautiful 20+ft. Arborvitae in front of my kitchen porch and it is being eaten from the top down by the bag worms that you describe. I am afraid to spray it with chemicals because it is located just above my well. I have been vacuuming the bags off that I can reach. This seems to work better that picking them but the upper half of the tree is higher than I can reach.

    I don’t know what to do. The worms are blowing over onto my porch and I am despirate. I so want to save this beautiful tree. I have spent many many hours vacumming, trying to save it.


  28. Will Says:
    4Avatars v0.3.1 v0.3.1

    Any bags you can’t reach will need to be sprayed unless you know of someone with a bucket truck and lots of time on his hands.
    Spraying the tree above your well shouldint be an issue since only a light coat need to be applied and its not enough to saturate into the ground.

  29. Shelby Says:
    4Avatars v0.3.1 v0.3.1

    Thanks for the information. I noticed my tree at my front steps was completely covered with these awful things. I had no idea what they were until today. I also noticed yesterday that jellow jackets are starting to sworm around the tree. Is my tree too far gone? Do I have to pull it up and replace it or is there something less costly and effective to do?? I am completely clueless and this tree is pretty much dead, I think. Right now I have my house on the market for sale and this tree (once beautiful) is now an eye-sore! please help!! Thanks, Shelby

  30. Allyn Paul Says:
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    Hi Shelby,
    if the tree in question is an evergreen (I suspect it is) and it is brown, then it is gone. Yank it and plant something new. best of luck with your sale on the house,

  31. Cathryn Says:
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    Hi Allyn,

    I’ve picked the bags off the arborvitaes and will use the systemic you recommned. Today I noticed a couple bags floating from threads on a mature ash tree. The ash is about 25 feet from the arborviatae. Should I be worried the ash will become infested? Is there a preventative I should use on the ash, the Bayer product maybe? Thanks

  32. Allyn Paul Says:
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    Hi Cathryn,
    you are seeing the bag worms attempting to move to new plant material. The ash is not their first choice, in fact, not even on their radar so the ash is not in danger. But if you have any evergreens anywhere else on the property, you can bet the bagworms will float over to them eventually. You may also see them hanging on your house if you have wood siding… once again, not eating, just searching.

  33. LGho Says:
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    Burning picked bag worms is not necessary, roasting them on a skillet will do fine and brings out a nice nutty flavor. If you put them into a fire pit you’re going to get ashes on them and who wants to chow down on ashy worms ?

    Yes, I’m just F’n around

    But on a serious note, Burning is not necessary.
    You can just simply put them into a container (I use a coffee mate creamer container) and take some Clorox Clean up spray (w/ bleach) and spray them down. In about 5 seconds they begin twitching and squirming around in a frantic attempt to get out of their bag only to find themselves in a puddle of Clorox Clean Up…. with in another 10 seconds they are dead. 100% kill, no maybe’s , Dead and can be thrown in the garbage.
    Not sure if it is just the bleach or if it’s the other chemicals and soaps clogging the pores mouths and eyes but none the less it works.

  34. Bob Galaska Jr. Says:
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    I am thankful that you have lots of pictures and information about and how to kill evergreen bag worms, as far as them not being north of mid-Ohio, guess what i got them in Aurora Ohio for the first time ever, Aurora is 35minutes North east of cleveland, to other be careful they can clean the needles off a 6 ft. blue spruce in two weeks, luckily i caught them in time.

  35. Dianne Longfellow Says:
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    I am so happy to find this website. I’m down along the Ohio River east of Marietta. I have 3 beautiful, well was beautiful, blue spruces in my yard planted years ago as a property divider. I have been picking off these horrid bags for 3 days. The trees are probably 15 ft high and I can only reach so far up. It is nice to know what to do but really sounds exhausting after these bag worms take over. I think I’m going to cut them down and put up a fence!

  36. Cathryn Says:
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    A couple of weeks ago I followed Allyns advice on the Bayer product. I also and picked about a gallon of worms from six 10′ arborvitae. Today I went over the shrubs again and picked off two dozen worms total!. Also all shrubs have new growth at the top. I hope it’s not too soon to say I’m out of the woods but so far I definetly see improvement.

  37. Allyn Paul Says:
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    Hi Cathryn, glad you are winning the bag worm battle. If you fertilize the plants this fall (like now) it will really help too.

  38. Bob Says:
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    I just found about 100 medium to large worms on 4 of my pine trees. There wasn’t a lot of damage, but what can I expect this late in the year?
    I had sevin, so I sprayed after picking off every one I saw. Do you think it’s too little too late?

  39. Allyn Paul Says:
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    Hi Bob,
    too hard to tell, but you should def monitor them over the next month or so. If you see more bags and worms, get the soil injected stuff.

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