BILLYWIG

"The Billywig is an insect native to Australia. It is around half an inch long and a vivid sapphire blue, although its speed is such that it is rarely noticed by Muggles and often not by wizards until they have been stung. The Billywig's wings are attached to the top of it's head and are rotated very fast so that it spins as it flies. At the bottom of the body is a long thing sting."

-JK Rowling