Bug Net

The Merchant stocks it, and it is the cheapest thing on his list that changes what you can do. Fishing does not really begin until you have bait, and this is how bait happens: most insects, worms, and snails go straight from the net into the bait slot. Critters also sell well enough that a handful of them covers what you paid, and a rare gold one is a small fortune on its own.

Critters produced by a statue evaporate when you swing at them, so a statue farm makes bait no faster than walking through a field does. Underworld critters are worse than useless with the plain net: it cannot take a Lavafly, Hell Butterfly, or Magma Snail, and trying burns you and sets you alight. That layer wants the Lavaproof Bug Net.

A captured Truffle Worm is the only way to bring out Duke Fishron, and it has to be used as bait out in the Ocean. A caught Prismatic Lacewing lets you decide when the Empress of Light arrives instead of triggering her the moment you notice one drifting through the Hallow. Both are worth a dedicated trip with an empty inventory slot ready.

The Golden Bug Net and the lavaproof version swing wider and faster, and they also cut down tall grass, vines, and cattails the way a sword does. Dragonflies gather on cattails, so the basic net catches them without destroying the thing that gathered them. If you would rather carry one net for everything, the Guide to Environmental Preservation stops the cutting and the problem goes away.

Anything you catch can be let go again by using it, so a full net is not a commitment. Combine a critter with a Terrarium and you get a cage that keeps the animal moving around inside it, which is the only piece of decor in the game that is also livestock. Bunnies have a darker future available to them as Explosive Bunnies.