Beetle eyes are a common potion ingredient.
In 1994, there were some beetle eyes among the squalor in the Shrieking Shack. Later that year, some got scattered on the floor of the Dursleys' living room when the Weasleys accidentally broke down the wall.
Over the course of his education at Hogwarts School of Witchcraft and Wizardry, Harry's trunk had accumulated a layer of filth along the bottom including, among other things, desiccated beetle eyes. Harry cleaned out this mess while packing for his final departure from 4 Privet Drive in 1997.
- Harry Potter and the Philosopher's Stone
- Harry Potter and the Philosopher's Stone (video game) (GBC version)
- Harry Potter and the Deathly Hallows
- Harry Potter Trading Card Game