In Megaman battlenetwork 3 blue where can you find the virus volcanest

The Undernet. Try searching Undernet 5, 6, and 7, using Collect, to ensure that you get their chip, and maybe oilbody to lure them out of hiding. Also, try searching Secret 3 with Oilbody and Collect--it'll take a while, and you'll run into a lot of Scuttle viruses, but you should find one eventually.