Tent caterpillar onslaught - any tips

This is turning out to be a brutal spring for tent caterpillars. I have sprayed all my fruit trees multiple times with BT, but it’s a losing battle. My fruit trees are mostly small (±60) 1st, 2nd, or 3rd year trees. Most have very limited foliage as I am training the majority as small espalliers against my fences. All my small fruit trees have no caterpillar nests. The problem is my neighbors large trees just on the other side of my fences are loaded with up to 50 nests per tree. The numbers just seem stacked against me.

No matter how many caterpilers my BT applications kill there’s probably 1000X as many left to continue the onslaught. I’ve killed hundreds of them today by picking them off my trees or squishing them on the fences as they cross over. No matter how many I kill it seems like a losing battle for the sheer numbers of them. Unfortunately, BT just won’t get the job done as they are all coming from locations I can’t reach on my neighbors properties.

Does anyone know any tricks besides using BT that can help kill this army of nasty critters? Even my chickens won’t eat the ugly buggers.

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About 5 year ago I had lots of tent caterpillars, and had have for years. I had a bag of B.t.
But it was several years old. I doubted is was still good .
And did not really have time to apply it properly.
So picked a very windy day , wind would gust from one direction then another.
I took a shop vacuum outside .took the filter out of it.
Waited for a gust of wind to come , turned on the vac .
Slowly added a table spoon full of B.t.
Then another, watching the dust ( B.t. ) swirl up high in one direction , then another. Fed the whole bag in the vac that day .
A little at a time different wind directions .
That was 5yrs ago have not noticed a tent caterpillar since.
My house ( shop vac . ) is on top of a hill surrounded by orchard,
and vast forest. I can not say for sure my vac. Duster is responsible. But I have not seen any tent caterpillars in years.
I am sure that dust went a long way .


I use a propane tourch with great success.


My old man’s favorite trick was to have a 30 foot aluminum pole with a rag soaked in oil that he’d use to torch their nests. Unfortunately I can’t do that because the nests are all in my neighbors trees. On the bright side if I can keep my trees from being totally defoliated my trees should get lots of sun as the neighbours trees hardly have any leaves left on them to shade mine out.


Well a few tricks I’ve learned to slow or kill tent caterpillars:

Round wire cages around trees don’t just help with deer. They help slow down tent caterpillars as they will wander around in circles a long time, making them far easier to spot and pick off.

If you are raising espaliers along a fence put a round bucket of water under the fence posts. These will drown a lot of tent caterpillars with little effort.

Use decoy branches from trees they like to eat and place them along the top of the fence or in piles on the ground. They will be attracted to these diversionary branches where they can be more easily killed with sprays or other methods before reaching your fruit trees.


Did you try to talk to your neighbor and offer your “help to get rid of that nasty creatures”?

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The neighbors on both sides are non residents. One side I’ve known for 50+ years and I spoke with them about this problem. They were fine with having me tackle it for them, so I cut a 3 foot buffer zone in the brush along their side of the fence and cut off all branches overhanging the fence. I then sprayed their lower foliage with BT. Unfortunately, most of the nests on their property were 30-50 ft in the air and inaccessible. This work did help quite a bit in reducing the numbers coming over the fence on their side.

The other recently acquired neighbors I do not know how to contact and they are rarely there. Their place is fenced and gated and I could not access their property without a passcode. Most of their trees are too high to reach the nests as well. They did have a gardener at their place on the weekend who removed some of the lower nests, which helped a bit.

Sadly, I can’t drop all my neighbors trees adjoining the fence line, (as much as I’d like to). :grin:

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I used to get these things off but once I just let them completely defoliate a blueberry just to see what would happen and the plant had its leaves back on a couple of weeks like nothing had happened. Had deer defoliated a young magnolia but same thing it just popped new leaves out on a few weeks

I know they won’t kill many of my trees. However, most are small newly planted trees and I think this will set them back a ton in sizing up and fruiting anytime soon. I have approximately 60 newly planted fruit trees, and the majority I turned into multi graft trees this year. My biggest concern is that defoliating my tender new grafts will kill a lot of them. Some grafts are just popping now and I don’t expect many will survive being stripped of their newly sprouted growth. I’m pretty sure some of my new grafts have been killed already.

It’s so disheartening to see all my new grafting efforts being slowly decimated. A lot of time, effort, and money going down the tube thanks to these nasty critters. I could have accepted my grafts not being successful a lot easier, but to joyfully watch them spring to life only to be devoured is very hard. The saddest part is I’m old and it’s a race against the clock to ever get to see the fruition of all my efforts. If I was young it would be nowhere near as devastating, because I’d have plenty of time to try again.

Good tip about decoy branches. I did notice the caterpillar congregation on prunings laying in the grass …but didn’t think to use this as an advantage!
Also I found that Tanglefoot covered tree spirals (or pipe insulation) on the trunk and uprights work to congregate and deflect caterpillars, even for espaliered trees.

I’m on my second 16oz bottle of BT mixed with Neem, but hard to measure the exact lethargic factor in caterpillars.


Having run out of tree spirals, I’ve switched to equally ugly fixes!
In hindsight, once I removed nests from trees, I should have gone solely with Tanglefoot for the trees. Spraying with BT and Neem gets expensive - should have saved that for the raspberries and strawberries.

Duct tape on old trees with fissured bark should not be a problem. For young trees with smooth bark I’ve heard people say that you can use duct tape applied sticky-side out.

I do recall the invasion about 10 years ago but I don’t recall it being this massive. When I step inside, caterpillars fall off my hair!

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I’m starting to see many cocoons with a single caterpillar inside,


And I also see a few new tents in fruit trees. Meanwhile the ground is a moving mass of caterpillars. I am taking some small satisfaction from my duct tape roadblock.


But the tall alders still have tents - so hard to figure how long this will last. Btw this phenomenon is strictly limited to rural areas with alder forests. Can’t find one caterpillar in town!

Moths emerge from cocoons after about 12-18 days so ought to see some noctural swarms of moths here around June 16th.

While this is definitely not an environmental solution (since there are beneficial moths flying at night) I’m considering plugging in my thrift store UV zapper to see if I can attract the tent caterpillar moths at night.


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Fortunately my infestation is starting to taper off a bit after a lot of hard work. I also changed my tactics a little bit. I’ve sprayed for the last 3 days on any foliage near the fence line on my and my neighbors place with some extra additives. I don’t like spraying my trees at this time of year with soap and horticultural oil. I figured I’d add those to the BT mix and use it on all the vegatation surrounding and leading to my fruit trees. This seems to have helped somewhat, and it seems to finally be dropping down to a manageable level.

At this point I’m happy that I’ve only lost a few grafts because of the caterpillars stripping them after recently breaking bud. I’ve had to do more grafting to try to replace vegatation on defoliated limbs where the leaves weren’t growing back. These grafts seem to have taken and they are coming to life now. I just have to be extra careful to try and keep the remaining caterpillars off my new grafts.

The bright side is so far this year is that there has been very limited aphid activity and no fireblight. If the aphids and firelight was like last year along with the caterpillars, I think I would have lost more than a few trees to that triple whammy. I’m keeping my fingers crossed that I’m over the hump and the trees will put on some good growth this summer without any more major problems.

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@tbg9b, my mother would always just take a long stick and break up the nest the tent caterpillars were in as soon as it began to form. I ended up buying 2 telescopic 21 foot long pool skimmer poles for a liquid propane flaming job that I had to do on 2 paper hornet nests before the black walnut tree was safe to climb, and the poles were lightweight, inexpensive and strong. Take large diameter hose clamps (available in the plumbing department of big box home improvement stores) and strap them together and you can reach way into a tree to break those nests open.

Many of the nests are in my neighbors trees and are 30-60 feet in the air and are not accessible as they are surrounded by thick underbrush and wild blackberry brambles.

Thanks for the tip though.

I used a propain torch on a stick.

I still have my old mans 25 ft long aluminum pole for burning out tent caterpillars. My father used this on caterpillars 50 years ago when we had all full sized trees where the caterpillar nests were 20+ feet in the air. I have taken out all the old tall unproductive fruit trees on the property that used to be magnets for tent caterpillars. I only have one very tall old pear tree left, but it was clean because it was far removed from the neighbors infested trees and mostly surrounded by conifers.

My current fruit trees around my home are are all, (with a couple of exceptions) under 7 feet tall. I do not require long extendo arms to cut or burn caterpillar nests from my fruit trees any longer as all my new trees are small form espaliers that can be picked without the need for a ladder. Its my neighbors trees that have been the problem with hundreds of nests far too high in the air to reach.

Creating new nests as they move along, and curling up in a leaf all to themself, are tactics of Forest tent caterpillars, so not unusual for those.

You can try increasing your bird populations, particularly orioles, jays, chickadees and nuthatches. How you do that is anybody’s guess. They are also eaten by bats and lizards too.

From what I’ve read these nasty infestations occur about 3 out of every 10 years. I have to deal with a couple nests of the Eastern variety every year, but I’ve gotten much better at finding the eggs before they hatch and removing them.

Good luck!

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