The Tomato Hornworm feeds on more than just tomato plants. They are also attracted to Potatoes, Eggplants and Peppers. They are hard to find during the day because their green color blends with the leaves the plants. If you find dark green dropping on leaves then you might find the worms underneath them. If you see stems that are missing leaves or wilting then you may have Hornworms. Leaves will also have wholes in them. To control the population, you can hand pick them and give them to your chickens if you have some.
To keep them away from your garden you can inter-plant dill, marigold, or basil. Tilling your soil may also help as well as attracting wasps. Here is an articles called “Tomato Hornworms: How to Get Rid of Tomato Hornworms” from The Old farmer’s Almanac.
Did you know that Hornworms glow under black light? Here is a video called “How to Get Rid of Tomato Hownworms with a $10 Black light” from Roots and Refuge Farm.