Firefly

Fireflies are passive flying mobs that can 'glow' at night.

Natural generation
Fireflies spawn on grass blocks at light levels of 9 or more with at least 2 block space above. They often spawn in groups of 4 during world generation.

Drops
Fireflies do not drop anything when killed. They drop 1 to 3 experience when killed by a player or tamed wolf.

Behavior
Fireflies wander and fly around aimlessly. Like other insects, they can scale up walls and will fly away from the player when approached. Fireflies make clicking sounds occasionally. They also glow at night, but this is merely for ambience, and does not provide an actual light source.