Amikor először belépsz Shady Sands-be, és beszélsz Seth-el, kérdezdd a radskorpióról. Mesélni fog a testvéréről, Jarvis-ról, akit megcsíptek radskorpiók és When you first enter Shady Sands and talk to Seth, ask him about the Radscorpions. He'll tell you about his brother Jarvis who has been poisoned and that you should speak to Aradesh for more information. This will activate the Stop the Radscorpions quest. You'll then be provided with a dialog option with Seth to be taken to the Radscorpion caves. Don't do this just yet.
Go talk to Razlo, and ask him what he knows about Radscorpions. Follow the dialog for more information to get the information about collecting the stinger in the tail.
Go back to Seth, and have him take you to the Radscorpion caves. He will not join you in taking them out, but you can optionally get Ian as an NPC before you go. When you've killed the Radscorpions, search the corpse to collect the tail. They're heavy, so factor that into your inventory.