Moth
From Halopedia, the Halo wiki
Moths are a type of insect that are typically nocturnal. They navigate at night using the light of the moon, which causes their well-known behavior of crowding around lights at night.
They are seen in the swamps of the level 343 Guilty Spark in Halo: Combat Evolved. They, along with the Sea Worms on the Silent Cartographer, are the only known species of Installation 04, although the calls of various other creatures are heard at certain points throughout the game but are unknown. These sounds are presumably from, owl-like birds, and crickets. In Halo Combat Evolved, they are harmless to the covenent and hamans alike.