You need 31 to get larupia furs, unless you buy them from other players.
Get any woodcutting axe (the higher the metal the better) and a knife, and a teasing stick, which you can buy from the hunter store in Yanille.
Go to the jungle, far to the south-east of castle wars. Search around here until you find large pits in the ground. Now cut down some of the nearby trees to get some logs, and click the pits to build traps over them. Make sure you build at least two, preferably close to each other.
Once you've done this, click one of the nearby Larupias to tease it, then make run to your trap. Click it to jump over your pit, then move out of the way. The larupia will either walk over the trap, and die, or jump over it. If it jumps, and you haven't moved, it will hurt you. If it dies, you can click the pit to get its fur and bones.
Be warned, that the larupia will be attacking you while you lure it to the trap, so you may want to bring some food to heal yourself.