A few weeks ago I fitted special screened bottom boards with oil trays as a method of controlling SHB. Well the results are in: they are fantastic with hundreds of the things killed in my traps and very few visible in the hive on inspection today. I am a convert, although I may swap the oil for lime as the oil has spilled and made a mess on my hive roof platform.

The pic is of poor quality but the black specks are beetles and you can also see some dead larvae.