I've had to deal with these little buggers twice now on new purchases. This is what I did, and it works.

Go to Walmart or a drug store. You'll need a gallon of distilled water, a 2oz bottle of Nix(for head lice), and a spray bottle. Poor out a small amount of water from the jug. Then poor the nix into the water. SHAKE WELL. Poor solution into spray bottle. Keep whatever you don't use in a dark area or covered.

Remove the snakes water bowl. Clean out any substrate. Wipe everything down. Burn all paper/paper towels used. Put new substrate down. Spray EVERYTHING in the cage, including the snake. Also spray around outside of cage. Go scrub water dish with soap and hot water. Go take Shower, then wash clothes in hot water. Wait 24hrs and put the cleaned water bowl back into the cage with the snake. Repeat every 5-7 days for 3-4 times.

Good luck!