Insect

Bugs are insects, found in various games throughout the series.

Butterfly
Butterflies first appear in Link's Awakening. If one butterfly touches a Deku Stick in Ocarina of Time or Majora's Mask, it will turn into a either a fairy or a bomb.

In Twilight Princess and Skyward Sword, butterflies are collectible items with different uses. In Twilight Princess, we have the ♂ and ♀ varieties of the Golden Butterflies, and in Skyward Sword we have the Blessed Butterflies.

Butterflies also appear in Oracle of Seasons, although Link cannot interact with them.

Joy Butterfly
Joy Butterflies are blue butterflies that appear as a result of certain Kinstone fusions in The Minish Cap. There are three different joy butterflies to catch, which will each either increase Link's speed in shooting arrows, digging, or swimming.

Joy Butterflies are small and slow and therefore are easy to catch. Link can just walk over them to catch it.

Bottle Bugs
In Ocarina of Time and Majora's Mask, bugs are that respectively can be stored in bottles. They can be found under small rocks or be purchased at the Medicine Shop. Each bottle contains three individual bugs which, when released, will scamper around for a few seconds, and then dig underground, never to be seen again. Their preferred breeding grounds are mounds of soft soil.

These seemingly insignificant bugs benefit Link greatly while he searches for Gold Skulltulas. If Link finds a mound of soft soil to drop them on, they will burrow into the soil and in so doing may reveal a Gold Skulltula.

Every time they are released, three bugs pop out. This can be useful to increase or maintain bug supply by releasing and re-catching bugs in new bottles. This trick can also be used for quick money in Ocarina of Time, as they can be sold to the beggar for 50 rupees per bottle.

In Majora's Mask, if Link releases a bottle of bugs near a mound of soft soil, different items such as Rupees, Arrows, and Bombs will come out. This happens everywhere, with the exception of the Swamp Spider House, where a Gold Skulltula is released instead, much like in Ocarina of Time.

Golden Bugs
The bugs of Twilight Princess, Golden Bugs, are found all over Hyrule. A child in Hyrule Castle Town, Agitha fancies these bugs and sent invitations to 24 bugs around Hyrule for the ball. Unfortunately, it seems none have arrived, and she asks for Link's help in bringing all the bugs to her castle. She will pay Link generously upon finding and giving her the bugs. Collecting them all leads to two wallet upgrades, each with a higher maximum rupee capacity. The collection of Golden Bugs is an optional sidequest and is not required for completion of the game.

There are 12 types of Golden Bugs, and a male (♂) and female (♀) of each type, for a total of 24 to bring back to Agitha for her bug ball. Both male and female variations of a single bug exist relatively in the same area, thus making the hunting for a gender pair easier.

Bugs in Skyward Sword
In Skyward Sword, bugs are a collectible item found in both the Sky and the surface. They can be sold to Strich at night time, or used to upgrade potions in Luv and Bertie's Potion Shop.

Bugs are caught either by rolling into a wall or a tree with the bug on it, to make it fall to the ground (This is unlikely to work if the insect has a high level of evasiveness), or by using a Bug Net purchased at Beedle's Air Shop for 50 rupees. The Bug Net can be upgraded into a Big Bug Net at Gondo's Scrap Shop for 100 rupees, three Tumbleweeds, two Ancient Flowers and an Evil Crystal. The larger Big Bug Net makes it easier to capture insects.

Trivia

 * Bugs in Ocarina of Time look like a miniature Tektite.
 * The Golden Bugs in Twilight Princess, are attracted by the light of Link's lantern.
 * In Twilight Princess, the menu description for the male and female snails mention that possibility that they might actually be the opposite sex. This is a reference to the fact that snails are actually hermaphrodites, and so there are no male or female snails.
 * If Link has Golden Bugs in his possession that he hasn't given to Agitha and he tries to leave Agitha's Castle in Twilight Princess, she angrily mutters to his back, "I know you have bugs..."
 * In Skyward Sword, bugs can be stunned by Link using Mushroom Spores

Gallery
''See respective pages for translations, see here for the translations for the bugs in Skyward Sword.