Hello Fred!
Something you can do now to cut down on future infestations would be removing and destroying any egg masses you may encounter in your bushes or nearby forest. While it may seem like a never-ending battle, attacking the pest at weak points in their life cycle is key to keeping them to a manageable level.
I think you would have a bit of success with spraying a pyrethrin and piperonyl butoxide based insecticide on the grass and rock drive way. I would re-apply once every three or so days when you are in the thickets of the infestation. However it should be noted that these organic chemicals are broad spectrum and may injure beneficial as well as problem insects. Applying Monterey Bt kurstaki to your berry plants would be the safest approach and it’s approved for organic production.
This bonide pyrethrin spray contains piperonyl butoxide and would fit your needs well.
https://www.planetnatural.com/product/pyrethrin-spray/
https://www.planetnatural.com/product/monterey-bt-kurstaki-bt-k/
Here’s a bit more information on tent caterpillar control you could delve into!
โhttps://www.planetnatural.com/pest-problem-solver/tree-pests/tent-caterpillar-control/โ
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Hope this helps! Good luck!