In my violin case up until recently I would close at the end of each practice. As of late, I open the case in the a.m. and close it at the end of day. I do a fair amount of traveling. Whenever we stay in a motel / hotel I always take it in my room. I am careful not to leave the case / violin sitting in the sun or by an air vent or in the car. I do not know if it is OK to leave the bow tightened all day but usually will loosen the hairs after each session.
Regarding dust mites: When I first got my grandfather’s violin I notice the hairs on the bow were loose so I had it re-haired. I vacuumed the inside of my case and well, the same thing happened. I found out it was those evil mites!!!! I ended up getting a new case. Can these mites do damage on the violin as well as the bow hairs? What the best way to get rid of them besides not getting them in the first place!!!!!!!