User blog comment:Lord Loss/Discussion of the Week: 3rd Generation Soundtrack/@comment-184.38.85.33-20120930180834/@comment-184.38.5.164-20120930210634

If you mean where than in the High Rank(and in the Bulldrome quest) in MHP3RD.Sometimes next to a HR Quest they have a mystery mark or icon http://images.wikia.com/monsterhunter/images/1/15/MHP3rd-Mystery_Icon.png next to the required monster letting you know their is a chance that a warning monster could come up.This monsters include Narga,Los,Tigrex,Jinouga,Deviljho and their subs.

In Monster Hunter Portable 3rd, Deviljho has a chance to appear after clearing HR5/HR6 quests as a Warning Quest Monster, as well as meeting it randomly while in Upper Rank quests (similar to Tri). If Deviljho appears via the Warning Quest, the player is given another 50 minutes to slay or capture it, and the supply box will be refilled. Even if the Warning Quest is failed, it will count as beating the initial quest