Firefly

The Firefly is a critter that appears everywhere at night in any season. Because it is not tied to a specific biome or weather, it can be encountered whenever the player is out after dark, making it one of the more common nighttime insects to spot while moving around the island.

Its broad availability means there is no special route or seasonal planning required to find it. If you are exploring at night, simply travel through any area and watch for the fireflies as part of the ambient wildlife. Since it can spawn throughout the map, it is best thought of as a general nocturnal critter rather than something associated with a particular region or event.