I tried using cypress leaves from a cypress tree in our back yard a few months ago. I wanted to use them for my Everglades Rat Snakes, because I am doing swamp-themed vivariums for them. In the end, I changed my mind because these particular snakes are Scaleless and cypress leaves are a bit "prickly". However, the method I used was:
(1)gather fallen leaves and soak them overnight in a bleach/ water solution of 1 gallon of water to a cup of bleach overnight.
(2)soak a second night in plain water.
(3)squeeze out as much water as possible and place on a tray and place in oven on low heat until the leaves were dry.
I didn't have any problems with bugs, but it seemed (to me) that the snakes were less inclined to burrow, and I assumed it was due to the afore mentioned "prickliness".
Best of luck!
~Beau