Felicia / learned about insects.
The subject is Felicia (the "who" of the sentence, the one who does the action that the predicate describes).
The simple predicate is: learned. It is a single, main verb in the sentence, which tells us the action of the subject, without explaining it or providing a context.
The complete predicate would be learned about insects. It concretizes the verb, including details about it (what the subject does, how does he/she do it; in this case what exactly does she learn).
