Red spider's eggs

Red spiders' eggs can be obtained in both F2P and P2P worlds. In F2P, they may be found near the Deadly Red Spiders (Level-27) in the Varrock sewers. There are two spawns of red spiders' eggs.

Another spot that the eggs may be found is inside the Karamja volcano. Past the gold rocks and skeletons can be found Deadly Red Spiders, with one egg spawn located in the center of the group of spiders.

Red Spiders' eggs can be given (along with Limpwurt roots and 5gp to the Apothecary in Varrock, as ingredients to make a Strength potion -- the only potion available to "make" in Free (non-paying/F2P) worlds.