As a matter of interest the chemical responsible for the light emitted by the firefly or lightning bug, as it is called in parts of the US, is luciferin. The light is produced when it is oxidized in presence of the enzyme luciferase.

The etymology of the name Lucifer is also interesting. It's meaning is derived from the Latin lucem ferre which means light bearer, it was the name given to the dawn appearance of the planet Venus, which heralds daylight and is known as the "Morning Star" or "Day Star" in English.

From Wikipedia:

"The Bible does not name the devil as Lucifer. The use of this name in reference to the devil stems from an interpretation of Isaiah 14:3-20, a passage that does not speak of any fallen angel but of the defeat of a particular Babylonian King, to whom it gives a title that refers to what in English is called the Day Star or Morning Star (in Latin, lucifer).[2] In 2 Peter 1:19 and elsewhere, the same Latin word lucifer is used to refer to the Morning Star, with no relation to the devil. It is only in post-New Testament times that the Latin word Lucifer was used as a name for the devil, both in religious writing and in fiction, especially when referring to him prior to his fall from Heaven."