Batflies are one of the most ubiquitous creatures in the game, appearing in all but one region. Due to how common they are, they form a substantial part of most Slugcats' diet.
Batflies can often be found swarming in rooms featuring white-tipped plants, which function as their nests. When they sense a threat, they attempt to dive and burrow into one, then reemerge from another, farther plant in the same room. Swarms often leave one these rooms if a large number of them are eaten during a cycle and migrate to another swarm room in the region. Other groups of Batflies can also be found migrating throughout a region, moving from room to room.
Sometimes, when resting upside down on a ceiling, Batflies attach to each other, forming stacks. If a Batfly with others attached to it from below starts flying, the attached Batflies may not separate, and it can end up struggling to fly. If Slugcat grabs a Batfly attached to a chain, the entire chain is picked up until the other Batflies fly away. This can result in strange physics if the Batflies are still attached to the ceiling.
Batflies seem to have a resistance to Echo's abilities to make creatures fall asleep, but only slightly as they still fall asleep if they move closer.
Though Batflies are often wary of the player, they are usually rather lethargic in their evasion, and can be caught easily by simply jumping towards them and grabbing. Batflies are easier to catch if you are above them — they have a simple flight pattern and hover in a single spot for a few seconds, which is the perfect time to pounce. They can also be hunted from afar by hitting them with Rubbish or Spears, killing them and causing them to fall to the ground. It should be noted that Batflies cannot be stored in a shelter for later consumption, and thus must be eaten within the same cycle. Batflies are attracted to Batnip, which can be used to lure Batflies over to the player where they can be more easily caught. Batflies can be used to distract certain creatures, such as Pole Plants and Monster Kelp, by catching a Batfly quickly and throwing it into the range of the plant. If the player grabs a Batfly with multiple others attached to it, they may have a small delay before detaching from the stack, which can be useful to gather large quantities of Batflies. Batflies often burrow into the white-tipped plants as shelter, so it is recommended to crouch down in a corner until Batflies emerge from the plants. It can also be taken advantage of by standing on top of the grass, allowing Batflies to fall into your hands.
If the rain is approaching, and there is little time to stop and eat, Batflies can be carried into a shelter. They are eaten automatically when Slugcat sleeps, adding a pip to their food bar. This can prevent a starvation cycle.