Final answer:
In the sentence 'There are colorful butterflies in Nevada,' the subject is 'butterflies' which is what the sentence is describing.
Step-by-step explanation:
The student asked, "There are colorful butterflies in Nevada. What is the subject in this sentence?" In English grammar, the subject of a sentence is the person, place, thing, or idea that is doing or being something. In the provided sentence, the subject is "butterflies" because they are the ones being described as colorful and present in Nevada.