identify the verb,subject in the sentence.a cloud of fruit flies hovered over the banana
A cloud of fruit flies hovered over the banana.
The easiest way to find the subject and verb is to put parentheses around the prepositional phrases. Subjects and verbs are never in a prepositional phrase.
A cloud (of fruit flies) hovered (over the banana)
That leaves:
A cloud hovered
I'm sure you can figure it out from here.