What is the name of the yellow and green Caterpillar's?

The yellow and green caterpillar you might be referring to is likely the larval stage of the Swallowtail butterfly, often known for its striking coloration. Another possibility is the Tomato hornworm, which is also yellow and green. Both caterpillars can be found in gardens and are known for their unique appearances. If you have a specific species in mind, please provide more details for a precise identification.