The Kithraya Hive - Act 1 Side Quest
Location: Eirulan + Kithraya Valley
Closest Portal: Kithraya Valley
Objective: Defeat the Kithraya Hive Queen
Reward: Queen's Husk + Random Loot & Gold
The Kithraya Hive is a Side Quest available to you in Act 1 of Dungeon Siege 2 by speaking with Tamari in the Terrace of the Falls in Eirulan. You can find the Terrace of the Falls by taking the lift near the Tavern/Inn down to the section of Eirulan you almost never visit. Your first time here you'll have to run a circuit around the entire area to drop the bridge next to Tamari, then you can access this location with ease later.
For this quest you'll need to defeat the Kithraya Hive Queen in The Lower Kithraya Caverns. The easiest way to get to the Kithraya Hive Queen is to take the Teleporter to the Kithraya Valley and travel directly east. When you get close enough you'll see the silver star on your map of the queen's location; a screenshot can be found below with her location too.
An alternative way to get to the Kithraya Hive Queen is to take the Teleporter to the Azunite Desert then go through the portal to the Eastern Greilyn Beach. It's a shorter run to the Kithraya Hive Queen from here but I imagine taking this route will be more confusing to most people.