Musher Bugs are so called because they feed not on a person's physical form, but upon his or her thoughts and memories, devouring them seemingly at random, although good or important memories are seemingly targeted first, with memories of anger and horror left until last. It could be that good memories *taste* better to them then horrible ones, but given enough time, they will devour every memory that they can. To the naked eye they are invisible, with magical werelight or a pair of Aetheric Goggles they appear to be silver caterpillars with see-through wings. Each one generally is full for a day after taking one memory, but they live in swarms of thousands. What stops these swarms from leaving a country-wide plague of memory loss is that when not devouring memories, they need very high levels of magical radiation to stay alive in this dimension for more then thirty seconds or so. It is thought that they come from another dimension and can only enter this one when some magical spell gone horribly wrong has torn a hole between it and our one.
One place where they can be found is in certain deep pools within the Sorcery Springs Geyser Basin ;elsewhere they can only be encountered in certain magical craters caused by the megaspell wars of many centuries ago that destroyed the Old Order.
If someone is unlucky or stupid enough to get into a situation where they can attack him, he or she only has a short time to escape or the brain will be sucked dry of memories, living the person with the mind of a new born baby. Now, the brain is not physically damaged;individual memories can be restored quite quickly, as long as someone else knows then and can remind the afficted person of them. But in the case of a person left badly affected or mindless, the only way to restore their mental function is to teach them the simplest things and move on from there. If reduced to babyhood, they will regain skills at the same level as an average baby...crawling within weeks or months, getting a personality within two years, learning to speak once more, in a sort of reverse of Alzheimer's Disease. Within five years they will be like a young child, within thirteen, an adolescent, and so on.