Question
Hello Greg,

My hanging Burro's Tail has a consistent thin film of light white powder on the
entirety of the plant.  It wipes off easily.  It doesn't seem to be dust.  I am
familiar with powdery mildew...which is usually spotty.  This isn't spotty at all.  
Can some cacti naturally creat this sort of thing on it?  What is it?

Answer
Alicia,

Yes, that is normal on your plant and a lot of succulents and cacti produce it, it is called "glaucous". I am sure it is a natural defense of some kind (especially in plants with very few thorns, which do provide shade), but I am not certain about that. Hope this helps. Check out this webpage: http://en.wikipedia.org/wiki/Glaucous

Sincerely,

Greg