This achievement requires you to wander in the desert midday. Many players have had luck in the Great Sand Sea. It might take 5-10 minutes of running around before you start experiencing any hallucinations, and after that you'll have to keep wandering around until you get the right one - raining bugs! Once you see the scarab beetles raining down around you the achievement or trophy will pop (but it might take a few seconds after the hallucination finishes)!