Interestingly, the process of fluorescence uses up some of the chemicals, and if the scorpion is exposed to UV for long periods of time, it stops glowing. After a few days, the chemical build back up, and it starts glowing in UV again.
It has also been found that young scorpions and newly molted scorpions don't glow, and it is thought that the chemicals that cause the glow play a role in the hardening of their exoskeleton.
Many studies have been done to find out if fluorescing in UV serves any function for the scorpion, with different results, but no one is sure yet if it serves any purpose, or if it is just part of the chemistry. We do know that glowing is not limited to scorpions. Some pill bugs, millipedes, and beetles will also glow in UV.