Anyone know how to "destroy" them?

Everytime I left click on them Geralt just says "I need to destroy them" well duh obviously, but how?

Bomb those suckers ;-)

Also try Igni or Aard, that might work. Didn't try.

Nothing,

signs or bombs dont work

Did you try the explosive ones, made with rebis and caelum? I don't know their English name, in the Polish version they're called "kartacz" which directly translates as "case-shot" ("canister shot")

Try the dwarvish craftsman in Floatsom, or other craftsmen. They should all be shown on the minimap.

Is it bugged?

I've checked everywhere for solutions and nothing in my journal states anything special about destroying nests

Anyone?

Come on people, someone must be doing the sidequests, or are you all rushing to end the game already?

well, grapeshot bombs worked for me. i don't know if you have to equip them though.
i equipped them, walked up to the nests and left-clicked to destroy them.
there can't be any enemies around though, you can only do it if you're not in combat mode

I did it and was hit by a nekkar an instant latter twice. They both went boom. Do you know all the locations of the nests?

Have Grapeshot bomb in inventory (not sure if it'd work in pockets, but probably).
Left-click on Nekker nest. Back away.
Make sure you're on the phase of the quest that says to destroy the nests (requires 2/3 Nekker knowledge)

Here is a map for the nests, I found it on gamefaqs

http://www.cswarning.dk/aetasguild/NekkerNests.jpg

Much obliged.

Grapeshot works for destroying the nests - that's what the "knowledge" tab in the Attributes section of the Character options says. I'm playing with the xbox 360 controller and it prompts me to press "x," which isn't the button for using a bomb. So be sure that you're following the prompt that says "destroy nest" rather than just setting the bomb up.

I think what Grunthex said makes sense. You have to have the appropriate knowledge of nekkars in your "knowledge." I killed a bunch of nekkars until I gained all of the knowledge. If that doesn't work for you then you can buy the book about nekkars in the bookstore across from the blacksmith in the nonhuman district.