From WoWWiki

Skitterweb Tunnels is an area of Lower Blackrock Spire, and the domain of the Skitterweb spiders. It is ruled by Mother Smolderweb, who contiously lays eggs to expand the population of her brood. Skitterweb Tunnels is spread over two levels leading via ramps and rubble from the lower reaches of Hordemar City up towards Urok Doomhowl's ledge.

Subzones of Blackrock Spire
Blackrock Stadium • Chamber of Battle • Dragonspire Hall • The Furnace • Hall of Binding • Hall of Blackhand • Halycon's Lair • Hordemar City • Mok'Doom • The Rookery • Skitterweb Tunnels • Spire Throne • The Storehouse • Tazz'Alaor