Maggot

Maggots are the larval forms of some varieties of fly, thought the term is commonly extended to the larva of insects in general. Maggots are not limited to non-magical insects, a certain species of magical giant grub exists. Luna Lovegood also believed in the brain-like Aquavirius Maggots, though it is likely that these do not truly exist.

If the Patronus Charm is attempted to be cast by a Dark or otherwise not pure-hearted wizard, who would otherwise be magically capable of casting one, rather than the intended effect of a spirit guardian bursting forth, a horde of maggots will be conjured from the caster's wand, which will attempt to consume the caster. The first recorded instance of this happening is with the Dark Wizard Raczidian.

For Christmas of 1996, Kreacher sent a package of maggots to his new master Harry Potter as a means to show his contempt towards him.

Appearances

 * Harry Potter and the Half-Blood Prince
 * Wonderbook: Book of Spells