How can i tell what's eating my tomato plant?

It could be whiteflies, aphids, or hornworms. Here's an article to help you:

https://homeguides.sfgate.com/treat-leaf-eating-insects-tomato-plants-92981.html

There is some information here:

https://pender.ces.ncsu.edu/2020/03/what-is-eating-my-tomato-plant/#:~:text=Take%20a%20closer%20look.,it%20down%20to%20bare%20stems.

Is your tomato plant planted in the ground? It could be an animal coming along and eating them. Ground hogs, deer, rabbits can do that. You might want to consider putting a cage around your plants with a covering so they cannot see or reach them.

If not a 4 legged critter, then consider planting Marigolds, a natural pest repellent. Google Companion Plants and see what repels garden pests naturally.

Take a look at this, it should help: https://www.youtube.com/watch?v=kBKk3SScCVQ

Hi Susie. Given what time of year it is, I think rabbits are eating in your garden. Spring time is when rabbits are multiplying with nests full of baby rabbits. I use shredded bars of Irish Spring soap to deter animals away from my garden. I recommend this because it has worked for me. You could also use pinwheels, pie plates, or anything that moves to scare wildlife away. Good luck Susie. Hoping all is well with you.

Usually if aa insect is eating you plant you will see them on the underside of the leave and by site and a little research you will know what is eating your plants.

Here's a post that might help - https://pender.ces.ncsu.edu/2020/03/what-is-eating-my-tomato-plant/#:~:text=Take%20a%20closer%20look.,it%20down%20to%20bare%20stems.

Tomato and tobacco hornworms are closely related large, bright green caterpillars that feed on the leaves of tomatoes, as well as angel trumpet tobacco, eggplant and occasionally peppers. They have a distinct single spine or “horn” on their rear end, but cannot sting. They often leave dark green round balls of excrement under the plant.

Mix up 1 tablespoon of baking soda, ½ teaspoon mild detergent and 2 ½ tablespoons of olive oil in a gallon of water to make a repellent for all kinds of bugs as well as a fungicide for blight and mildew on the tomato plant leaves. Shake it well before spraying and repeat every week for it to be effective.

Hi Susie, Your plant is probably being attacked by hornworms. Despite their large size, these bright green caterpillars can easily hide among tomato leaves, staying out of sight until they have eaten most of the plant's foliage. Inspect your plants for hornworms now before they strip it down to bare stems. I ahve attached a picture for you as well.

My baby tomato plants were being dive bombed and eaten by birds , who I believe were feeding them to their young. I'd never heard of that before, but I watched them do it. Stripped the stems bare.