Drops
Rates listed as Classic mode unless the row says otherwise
two ways to start the fight
The intended route is the larva hanging inside a bee hive in the underground jungle. Hit it and she appears on the spot. The repeatable route is an Abeemination, usable at any hour of the day anywhere in the jungle, surface or underground, so she can be refought as often as you can build the summon. None of this is required for progression. You fight her for the loot and to open up the Witch Doctor.
you will summon her by accident
The larva breaks like a pot, so any damage at all counts, not only a deliberate swing. An armor set proc, a Star Cloak, a whip reaching through a wall, a stray bouncing projectile: all of it pops one. This bites hardest late in a run, when you are casually clearing the jungle and something offscreen sets her off behind you. The Guide to Environmental Preservation does not protect larvae the way it protects plants, so there is no way to switch the hazard off.
Bigger hives sometimes hold two or more larvae, which is common in drunk world seeds. Fire something like the Water Bolt into one of those and you can end up fighting two queens at once.
the three attacks
She always opens with the charge. She lines up horizontally with you and rams through three times in a row. The second pattern is a hover where she seeds the air with bees, in batches that get larger the longer she keeps it up. The third is a stinger barrage, alternating between sitting above you and swooping in from overhead while firing pulsing yellow stingers that poison on contact.
The bees themselves barely hurt. What they do is shove you, and being pushed into an incoming charge is what actually kills you. They also fight other enemies and take damage from them, so anything else loose in the arena, including something you released from a statue, will pull them away from you.
what expert changes
Her attacks accelerate as her health falls rather than running at a fixed pace, and the charges are what escalate hardest. Late in the fight she can string six of them together before switching to anything else, fast enough that reactive dodging stops working and you need a route planned in advance. Her defense also climbs as she weakens, so a low damage build finds the fight getting harder the closer it is to over.
On top of that, touching her poisons you, and the duration on higher difficulties is long enough to matter between hits. The bees she spawns are larger and considerably tougher, and ignoring them stops being an option.
leaving the jungle makes it worse
Fight her outside the underground jungle and she enrages: more aggressive movement and a much faster stinger rate. There are two grades of it. The surface jungle and other underground biomes give you the milder version, and any other surface biome gives you the full one. There is no biome where she gets easier, which is why arenas hollowed out around a hive are the standard.
she does not let go
Distance does not despawn her, which is unusual. Mirror out and she crosses the whole map to reach you, and if you land somewhere outside the jungle she arrives enraged and considerably more dangerous than the fight you ran from. In multiplayer she locks onto one player and only switches when that player dies. The only way to end the fight without killing her is for everyone in the world to die at the same time.
gear that helps
A Bezoar is the best single pick, because poison is most of the incoming damage on higher difficulties. Knockback immunity from a Cobalt Shield or Obsidian Shield is second, and if you have neither, a grappling hook anchored to a block does the same job for free. Piercing arrows clear bees in bunches for ranged builds, sentries handle them passively while you focus on her, and on classic difficulty a spinning flail deletes anything that comes close without you having to aim.
The Shield of Cthulhu dash can block a charge outright if the timing is right, though it gets unreliable as she speeds up. The honey pooled in the hive gives passive regeneration and blunts the poison, but it slows you badly, so dip into it between attacks instead of fighting from inside it.
after she dies
The Witch Doctor can move into a spare house, the Angler opens up two more quest fish, and the Traveling Merchant starts carrying the Gray Zapinator. Her coin drop is generous for how cheap she is to resummon, so she doubles as a money loop while you are still in the jungle. Kill her after a mechanical boss and she can also produce the Yelets, which normally only comes from hardmode jungle enemies.