Corflute makes good traps,
another method is if you can get the 4.5mm corflute, is to paint the side black (purely to darken the walls and not to let light in)
dip one open edge in melted wax, and them place in the hive.
the holes are small enough to allow beatle in and not bees. but the beetles can not turn around and they can't walk backwarks, so they are traped until you come and clean them out, and hot water works a treat.