What is the green caterpiller boring holes in the barn wood. About 1/2 unch long, only 1/16th around. Looks like they are coming from the ground, up the cement foundation and going back into existing pin holes in the siding. I imagine to lay eggs for the winter larvae, to start the cycle all over.
Where I am from we call those things "Barn Eaters"... not to be confused with your more common "Shed Eaters" and "Outhouse Eaters".
My guess is that the caterpillars are part of a life-cycle of a local wasp, mud-daubber, hornet, or other kind of flying insect. It's easy to ignore the relationship, but my experience is that these types of insects are in their most destructive stage as a caterpillar, especially in a garden. You would probably want to eliminate as many of these specific flying insects before they can lay eggs and larvae and turn into the caterpillar. That would cut down on their population in the caterpillar stage as well.
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