Was there for over 3 hours last night, saw him twice, once in the beginning, and once at the end. Many of the spiders there share aggro, and Naegarch seems to tie into that, too, although it's all spiders there. That wasn't a problem for my 21 Hunter.
He is not on a 3 minute timer. He seems to be connected to the spawn timer for the cocoon loot containers that spawn at the site, which is about 10 minutes. He also either roams, or appears in different spots. He dropped Naegarch's Eye and the Sapphire Shard both times.
I was not aggro with the spiders after the kill, just during the battle. After, I was ignored by the grey (to me) spiders until I attacked them.
Also, the image appears to have been updated. He no longer appears the same as all the other spiders. He's much larger, and fairly colorful to boot.
Edited, Sep 11th 2008 3:57pm by Kingbobb
Edited, Sep 11th 2008 3:59pm by Kingbobb