On Porter bee escapes:
 
I have been told that they work well when the nights are cool, as the bees
leave the super to cluster in the cold, and then can't get back.
 Unfortunately, near Washington DC we take off our supers during the hot
summer months.  Since the bees won't leave the supers at night, the Porter
bee escapes won't work here.
 
Personally, I use a fume board with Benzaldehyde (synthetic oil of almonds)
with excellent results.   The stuff smells like almonds, unlike the "gags
buzzards" smell of Bee Go.
 
W. G. Miller
Gaithersburg, MD