Answer: The most common would be the tomato hornworm, it is huge and can eat a huge quantity of plant material seemingly overnight. Check the undersides of the leaves and remove it. However, if it has bits of rice-like material sticking out of it then it has been parasitized by a beneficial wasp. In that case, leave it alone as it will help develop the local population of predators for it. Here are some photos to see if that is what you have. You may need to cut and paste the complete url into your browser to make it work correctly.
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