The egg of the Doxy is a type of egg that is used as an ingredient in the Girding Potion which is black in colour. Cormac McLaggen once ate a pound of doxy eggs on a bet, which caused him to miss the tryouts for the Gryffindor Quidditch team during his sixth year. Being that the Doxy is a fairy-like creature, Bowtruckles will apparently eat their eggs as readily as fairy eggs, as Aberforth Dumbledore once stated that if the Trio tried to head back out into Hogsmeade while the Caterwauling Charm was still active, then the Death Eaters would be on them "like bowtruckles on doxy eggs".