From Zelda Legends Wiki
Keese is a bat that makes a noise when it comes close, and they travel in packs. The Keeses are one of the smalles enemies in Legend of Zelda series, and they are sometimes the most annoying ones of them.
There are some other versions of Keeses, like the Fire Keese and Ice Keese. They are all same, except they have different abilities. They all fall down from one shot, except the hit of a Boomerang. The easiest way to defeat them is to shoot them with a Bow.
The Keeses appear in almost the all of the Zelda games.