Towers are the real problem against UD. Ghouls can take advantage of slowed huntresses and Crypt Fiends could kill your meat fast enough for the ghouls to slaughter your archers. I once hoarded ghouls behind my 2 graveyards (was going necs and needed defense). Then when the 2 teams of hunts came they tried to attack my mine and they were easily destroyed by my nerubian towers and my 15+ 1/1 Ghouls with Cannabalize. Defeating UD can be a challenge for the Night Elf player, because of poor constitution. This is where my friend AoA (Angle of Attack) comes in ^_^. There is a difference between attacking fiends head on, then from behind or from the side. The side is your best bet for destroying these spiders, since there will be lesser amounts attacking then when you hit them head on. Focus Fire and kill them. The glaives will weaken the next one and so forth, but you could still lose a considerable amount of men. Archers could help, Elune's Grace reducing thier damage, but they dont do much damage themselves. I AT with a friend and it gets imperative to kill fiends and such to keep his riders from being slaughtered. So really, stopping the ghouls isn't the annoying part (until they get Frenzy) its the fiends that piss people off. If you tech to bears and mg, you should stand a better chance (seeing how mg take 12 less damage and 50% less from fiends and bears easily kill them). If you still want to use hunts, learn Moon Glaive so you can weaken one more fiend with ff.
Then again... siege > hunts