Answer: Your lemon tree definitely needs to be inside this winter, and it's best to move it inside before the nighttime temperatures drop much below 50F. As for the damaged leaves, I suspect a caterpillar fed on them and he (or she) is long gone now so no spraying is required. Weevils don't bother citrus leaves and while slugs might crawl up the trunk and munch on the leaves, it would be quite unusual. I'd move the tree indoors and give it a cool shower to rinse off any hitchhikers. Give it bright light and water when the soil begins to dry out. Because there will be a big swing in the temperatures between indoors and out, expect your tree to drop some leaves until it acclimates to growing indoors.
Best wishes with your lemon tree!
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