Shadow Insect

This is the term used by the Spirits of Light in LoZ: Twilight Princess when they refer to the dark creatures that steal the Tears of Light. When the monsters steal the light of the land and bring Twilight to each region they conquer, those monsters take on the form of insects invisible to the naked eye. Link must use his senses in his wolf form to detect and kill the insects to refill the Vessel of Light given to him by each spirit, and unblanket the land from everlasting twilight. Link is required to help three spirits who were attacked and had their light stolen in order to completely stop the twilight realm from expanding across Hyrule.

These creatures, although called dark insects by the Spirits of Light, are also properly known as Twilight Parasites.