The Bottle Bug is a Bug that appears exclusively within Ocarina of Time and Majora's Mask. These bugs prefer to burrow in small holes under rocks and bushes. Link can scoop a bug into an Empty Bottle or purchase it in the Medicine Shop for 50 Rupees.
If Link releases a bug near a patch of Soft Soil, the bug reveals a Gold Skulltula. In Majora's Mask, Link can release bugs in patches of soft soil to receive Arrows, Rupees, or Bombs. If a bottled bug is released, three bugs come out from the Bottle, which gives Link the ability to catch them again and increase the bug supply. This can be done to make a good amount of Rupees as Link can scoop all but one bug, release it, and catch the bugs coming out of the Bottle, and repeat the process. Bugs can be sold to the Beggar in the Market as a child or Kakariko Village as an adult for 50 Rupees.