What animal is it ?

No.1 This is a very small animal. It has a green body, but its belly （肚子） is often white. It has four legs .Two of them are long and two of them are short. It has two big eyes .It can often make a loud sound in the evening or at night in summer. It is a good high-jump player. It likes to eat bad insects in the field. It is an excellent helper of farmers. It often lives in the field. What is it?

----It's a frog.