But what about DEET? I have Watkins 28.5% DEET lotion. I think it doesn't damage natural fibers. This is a bush shirt, intended to be worn in mosquito infested country.

I am a huge fan of Duluth Trading - www.duluthtrading.com and their performance work shirt, in chambray + coolmax is my go to when it's hot out, and I need to do a lot.

I never wear cotton. To demonstrate the advantages of this to myself, I often hike in the rain without raingear when the temps are just above freezing. I'm wet, but still warm, and my clothing dries quickly.

Clothing made for runners is excellent hiking clothing.