Stinkbug

Which of the two surface critters gets to appear is decided by a hidden roll at every dusk, and again whenever you load the world. One outcome switches stinkbugs on and locks butterflies out, the other does the reverse, and either winner can still be switched off afterward so that you get neither. That gives you a free reading of the sky. If butterflies are drifting past your door, no stinkbug will spawn anywhere on the surface until the next roll. Do something else and check tomorrow.

Even on the right day the conditions are narrow. You have to be out on the surface in daylight, it cannot be raining, a Graveyard shuts them off, and the wind has to stay fairly calm. A storm blowing through is enough to stop them entirely. When they do appear it is usually a small cluster rather than one bug alone, so a still, clear morning is worth more than an hour of wandering in bad weather. Recent versions raised their numbers on the days they are allowed to spawn at all.

Any bug net will scoop one up, and it rides in your inventory until you set it down somewhere else. Combining it with a Terrarium is a door that only swings one way. Once it becomes a Stinkbug Cage the bug is gone for good unless you drop the furniture into Shimmer to split it back apart. They are also fragile enough that anything wandering nearby can kill one before you close the distance, your own stray shots included, so hold fire when you spot one.

As bait it sits near the bottom of the pile. Fine for an early Angler quest when the box is empty, not worth a slot once you have anything better. The real reasons to keep a few are the Flymeal and the Stinkbug Blocker, plus the cage if you want something on a shelf that moves.

Real stink bugs take the name from a chemical they let off when something disturbs them, and descriptions of the smell run from strong spice to cilantro. The game commits to the cilantro version. It shows up in the flavor text of both craftable items and in the bestiary line about them getting into houses you thought were sealed.