Bug Net

[cass1011]

When and how do I get a bug net?

[Buffmania]

Those aren't in the base game, you've got to install a mod.

There's a butterfly hutch furniture item that you can buy from the desert trader that will spawn some butterflies indoors in the base game.

[iaregamertom]

You buy it from the merchant but first you have to get one gold or more in your inventory and have a place for him to live, oh,, yea, you also need to be playing Terraria ...