[Fred Reich]

I have about 800 Aronia Berry bushes trying to grow organically. Am surrounded by woods (central Indiana). Last Spring there was an invasion of caterpillars coming out of the woods and eating on berry bushes. They have to cross grass areas and a rock drive way to get to the bushes. In minutes I could step on hundreds but they just kept coming. Just on the edge I counted at least 15 tents 20 to 30 feet up in trees. They just seem to come all day long (never see them going back). Can I spray the grasses they have to cross to kill them or does it have to be the plants they are eating? as the infestation lasted for a couple weeks and the product is affected by the sun should I spray every day. Know they will be back because there are the little white cocoons everywhere. Any suggestions, recommendations will be greatly appreciated.
Thanks, Fred

[Eric Vinje]

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!
​https://www.planetnatural.com/pest-problem-solver/tree-pests/tent-caterpillar-control/​
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Hope this helps! Good luck!

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