Prismatic Lacewing

The Prismatic Lacewing is a rare butterfly Critter that spawns in the Surface Hallow during night time after Plantera has been defeated. Killing it summons the Empress of Light boss, however it may not be recommended to fight it during the Day. As well as this, the Lacewing can be caught with a Bug Net, and be used to craft a Prismatic Lacewing Jar or alternatively, released again to summon the Empress of Light.

Tips

 * It is best to catch it even when you don't want to fight the Empress of Light, instead of looking for it later.
 * You should take any summons off while farming, in case it kills the Prismatic Lacewing.