A ladybird is usually a charming sight, but here she is something harder to swallow. The speaker begins by calling her "a hard pill," and the poem goes on to show how a cute visitor turns into an unwelcome presence. There are suddenly too many of them, slipping into every crack of the house, crowding the window, and filling the rooms with the sharp smell of their defensive spray. The speaker's tone moves from amusement to irritation and then to unease.
The final lines shift the mood. Watching her fold and unfold her wings, the speaker wonders what she is so afraid of, and imagines the wings as a letter holding the last words of someone who died in a fire. The beetle stops being a pest and becomes strangely sorrowful, almost haunted. The poem leaves us with both annoyance and pity: a small, anxious creature that the speaker can't quite hate, even while it takes over the house.