PSA: For those with coniferous trees... bagworms don't look like bugs at all

[CountryBoy19]

I have a windbreak of cedar trees near my home... for the last few months some of them have been dying.

I'm no slouch when it comes to a green thumb etc and I'm usually fairly knowledgeable when it comes to pests and chemical applications etc. I hold a license from the Indiana State Chemist to buy/use restricted use pesticides.

All that being said, you would think I would know how to identify pests on my trees. Apparently I don't. I looked high and low on the trees checking for root damage, foliar damage, trunk damage etc. The trees were losing foliage but I couldn't figure out why; it appeared the trees were just dropping foliage.

Tonight while once again checking for explanations I randomly grabbed what I thought to be a "seed pod" type of thing hanging from the tree and began picking at it as I mulled things over in my mind. Next thing I know a worm is peeking his head out of that pod looking at me. WTF? I pick another one and pull it apart, another worm. You ***********, pick another pod, same thing... son of a *****, the answer was right in front of me the whole time...

Off to google to see just what I have: It's called a "bagworm" and this is what it looks like on the tree

They weave bits of foliage from the tree into their protective silk cocoon to disguise themselves from predators. Seeing as how I've never seen these bastiges before or even heard of them, they sure fooled me... come to think of it, these suckers have been on my trees for a few years and it was just now this year they got bad enough to start killing the trees...

Just fyi, if you have coniferous trees, cedar especially (it's one of their favorites) watch out for these suckers.

The cure: heavy dose of insecticide (several of them will provide control according to online sources), I used permethrin, approximately 25 gallons of spray at 1/4" oz of 33% permethrin per gallon of mix. I hope to see LOTS of these suckers dead in the next couple days...

 

[Restroyer]

I had the exact same thing a few years back at a different house. They were really tough to kill and my trees were so tall I couldn't reach all the evil things. I killed off the ones on the lower part of the trees but the ones on the upper part destroyed the top of the trees. When the ones I had died their cocoons still stayed on the branch which made it real tough to see if I had killed them. Good luck, they are a tough bug to kill.

 

[GodFearinGunTotin]

Yeah, I've got a row of arbovitea trees around my carport. Last year, I was mowing around it and noticed a bunch of the little suckers crawling on the ground next to the tree in one corner. The next thing I know, that tree is almost dead and several others were infested with them. The ones in the OP are quite advanced. This year I caught them earlier. They did quite a number on one of my trees but I think I got them this year before they could demolish anything.

If you'll notice, you'll see little, miniature versions in your trees--maybe 3/8" long, starting about a month ago (in southern Indiana). You'll also notice little peices of tree needles on the ground around the tree being munched on (I'm talking about arbovitae infestations here). You'll also notice, as they grow, you can spot the live ones because there'll be little bits of new (and green) tree needles attached to their cocoons. You'll also be able to see them moving. At first glance, the movements may look like the wind blowing and shaking them. But if you look carefully, you'll see the movements are intentional.

I used liquid Sevin to kill mine. An ounce or so per gallon of water in a spray pump does a good job on them. You just have to be sure and go back after a week or two because you'll miss a number of them the first time you spray. As was mentioned, after they die, their cocoons still hang on. But if you feel of the shells, there's no mistaking a living one with a dead one.

 

[Leadeye]

Malathion is another good bagworm blaster.

 

[CountryBoy19]

I had the exact same thing a few years back at a different house. They were really tough to kill and my trees were so tall I couldn't reach all the evil things. I killed off the ones on the lower part of the trees but the ones on the upper part destroyed the top of the trees. When the ones I had died their cocoons still stayed on the branch which made it real tough to see if I had killed them. Good luck, they are a tough bug to kill.

You have to heavily wet the tree so the chemical soaks through their cocoon, otherwise they have to ingest enough chemical from feeding and that takes longer. The bagworm control document I read last night said to wet the tree from outer foliage through to the trunk until chemical was dripping from the branches. It helps to have an adjustable spray wand on with a higher pressure output. I have a commercial hand-held pump sprayer that I used and I adjusted it to spray a solid stream to penetrate all the way to the trunk. I went through 25 gallons to spray 15 trees ~10 feet tall (that is a HEAVY application). It seems to have worked. After only 24 hrs I couldn't find a single live one, all of them were dead as far as I could tell. Many were trying to crawl completely out of their cocoons but it was clear they didn't make it all the way out before succumbing to the wonders of permethrin... I LOVE that stuff (just have to be careful because I also have honeybees)

Yeah, I've got a row of arbovitea trees around my carport. Last year, I was mowing around it and noticed a bunch of the little suckers crawling on the ground next to the tree in one corner. The next thing I know, that tree is almost dead and several others were infested with them. The ones in the OP are quite advanced. This year I caught them earlier. They did quite a number on one of my trees but I think I got them this year before they could demolish anything.

If you'll notice, you'll see little, miniature versions in your trees--maybe 3/8" long, starting about a month ago (in southern Indiana). You'll also notice little peices of tree needles on the ground around the tree being munched on (I'm talking about arbovitae infestations here). You'll also notice, as they grow, you can spot the live ones because there'll be little bits of new (and green) tree needles attached to their cocoons. You'll also be able to see them moving. At first glance, the movements may look like the wind blowing and shaking them. But if you look carefully, you'll see the movements are intentional.

I used liquid Sevin to kill mine. An ounce or so per gallon of water in a spray pump does a good job on them. You just have to be sure and go back after a week or two because you'll miss a number of them the first time you spray. As was mentioned, after they die, their cocoons still hang on. But if you feel of the shells, there's no mistaking a living one with a dead one.

Yeah, I wish I would have known all that a month ago; I wouldn't have watched my poor trees be eaten alive by a bug that camoflages itself so well... now I know... they won't be so lucky in the future...

 

[GodFearinGunTotin]

You have to heavily wet the tree so the chemical soaks through their cocoon, otherwise they have to ingest enough chemical and that takes longer. The bagworm control document I read last night said to wet the tree from outer foliage through to the trunk until chemical was dripping from the branches. That is what I did and it seems to have worked. After only 24 hrs I couldn't find a single live one, all of them were dead as far as I could tell.



Yeah, I wish I would have known all that a month ago; I wouldn't have watched my poor trees be eaten alive by a bug that camoflages itself so well... now I know... they won't be so lucky in the future...

I hear ya. I learned when I darned near lost a blue spruce tree years ago. I'd always seen those bags but until then, I'd never seen them cause any lasting damage. Now I know. Starting in June, I watch out for them. It just seems like one day, you're ok...then one day your trees are crawling with them.

 

[IndyDave1776]

My standard response to worm/caterpillar type pests is the application of a torch. Aside from being time consuming given the decentralized placement of these pests, how does fire work on them?

 

[GodFearinGunTotin]

My standard response to worm/caterpillar type pests is the application of a torch. Aside from being time consuming given the decentralized placement of these pests, how does fire work on them?

I never thought about a torch. But seeings how the critters are sometimes back into the tree/shrub, it seems like the risk of catching the entire plant on fire might be kinda high.

 

[CountryBoy19]

My standard response to worm/caterpillar type pests is the application of a torch. Aside from being time consuming given the decentralized placement of these pests, how does fire work on them?

They're pretty evenly spread across all foliage of the tree so I think a torch would harm the tree just as much or more than the worms are... The control options I saw are hand-picking or heavily wetted pesticide application.

 

[jamesb]

I lost a beautiful blue spruce to them in PA. I had never seen them before, saw a few of them the year prior, thought they were small pine cones. The next year they hatched and devoured the tree, had to cut it down. Was an ongoing battle to keep them out of the other pines. I treated them with malathion and hand picked any I saw in the pine. Nasty little things. I have a lot of pines that line my drive and I am always on the look out for anything that even resembles them.

 

[CountryBoy19]

I lost a beautiful blue spruce to them in PA. I had never seen them before, saw a few of them the year prior, thought they were small pine cones. The next year they hatched and devoured the tree, had to cut it down. Was an ongoing battle to keep them out of the other pines. I treated them with malathion and hand picked any I saw in the pine. Nasty little things. I have a lot of pines that line my drive and I am always on the look out for anything that even resembles them.

So far I have seen no signs of life from any of them. I will certainly keep an eye out for signs of life so I can nuke them from orbit a 2nd time if I have to... I'm guessing they will be back next year because I don't think permethrin gets their eggs...

 

[Hornett]

I used malathion but I don't remember the actual solution.
You have to be sure and spray every branch of the tree to be sure all of the eggs die also.
I remember that tree smelling like malathion every time I walked by for weeks afterward.
It killed them though.