Fly Racing | POEM

Two siblings lie in a tent, watching flies on the roof and creating a race with names for each fly. Their father interrupts, annoyed by the noise at 5:30 AM, and tells them to be quiet. After he leaves, the siblings continue to laugh quietly, enjoying their imaginative game.

What does the narrator mean by 'the later thing'?

Describe the emotions of the narrator and their brother while they are in the tent.