i found this research.
combining this with a screened bottom board to aid in ventilation could
provide some protection and prevention.

Controlling small hive beetles (Aethina tumida Murray) in honey bee (Apis
mellifera) colonies using a modified hive entrance. Ellis, James D., Jr.,
Keith S. Delaplane, H. Randall Hepburn, & Patti J. Elzen. 2002. American Bee
Journal 142(4): 288-290

ABSTRACT This study was designed to test whether colony invasion by adult
small hive beetles can be reduced by replacing the regular entrance of a
hive with a ¾-inch (2-cm) PVC pipe located 3-4 inches (7.6-10.2 cm) above
the bottom board. Colonies with pipe entrances had significantly fewer adult
beetles (46.9 beetles / colony) than open colonies (107.7 beetles / colony).
Pipe entrances did not directly affect the amount of sealed brood in a
colony nor the temperature inside colonies. However, brood significantly
affected temperature inside colonies and there was a tendency for reduced
brood in colonies with pipes; temperature increased as the amount of brood
in a colony increased. Brood did not affect the number of adult beetles
present in colonies. This experiment shows that modifying a colony's
entrance may help control small hive beetles, but more work is needed to
offset unwanted effects of reduced colony entrances.



_________________________________________________________________
Protect your PC - get McAfee.com VirusScan Online
http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963