Learn Italian: Ho paura che l'insetto voli nella stanza. - I am afraid that the insect is flying in the room.

Ho paura che (I am afraid that) expresses an emotion. In Italian, expressions of emotion or attitude followed by che require the subjunctive mood in the second part of the sentence. Because of this, the regular present tense vola changes to the present subjunctive voli.

If the sentence was 'I am afraid of flying', would I still use the subjunctive?

No. If the subject of both actions is the same (I am afraid, and I am the one flying), you drop che and use di + the infinitive verb: Ho paura di volare. You only use che + subjunctive when the subject changes, like it does here from 'I' to 'the insect'.

Volare is an -are verb. Why does it end in an -i here?

In the present subjunctive, regular -are verbs switch their ending to -i for all singular subjects (I, you, he/she/it). This means che io voli, che tu voli, and che l'insetto voli all share the exact same ending.

Why is it nella stanza rather than in la stanza?