I used to think that maybe [Ladybug] was a scientist who got stung by a radioactive ladybug while strolling at the Cité des Sciences. But the more I think about it, the more I believe it's actually the earrings that help Ladybug to transform, so the whole bug-bite theory kind of went out the window.
The Ladybug Miraculous are earrings that, whenever Tikki inhabits them, transform the wearer into a ladybug-themed superhero, who possesses the powers of good luck and creation. The earrings are currently owned by Marinette, who uses them to turn into the heroine Ladybug.
In general, the earrings are circular with a smooth surface and a silver lining. When Marinette isn't Ladybug, the earrings are black. However, when Tikki goes into the earrings while Marinette is transformed, they become red with five black spots in a quincunx pattern. As Marinette starts running out of power, the earrings make a beeping sound and the dots start disappearing one at a time as an indication of how much time she has left.
The Ladybug Miraculous grants its wielder incredible powers of speed, endurance, and strength. Its special weapon is an unbreakable yo-yo, which can be utilized as both a weapon and a communicator. Its special superpower is called the Lucky Charm, giving the user the ability to summon a useful object in order to obtain their goal, like defeating a villain. As long as the superpower isn't used, the wielder can remain transformed indefinitely. However, as soon as the superpower is used, the wielder loses power and the transformation usually wears off in five minutes.
Legend has it that if the Ladybug and Cat Miraculous are used together, the holder will achieve absolute power.
The NYCC sneak peak of the upcoming Miraculous powers.
The Ladybug Miraculous also seems to have other magical abilities. These abilities seem to be related to objects known as the Stone of the Sun, the Stone of the Moon, the Pearl of the Sea, the Pearl of the Heart, and the Pearl of the Mysteries.