Hi All

I should clarify, that I am not recommending the adoption of holes in brood
boxes or supers.

The vents that I originally referred to were of perforated metal with holes
of about 3 mm diameter (1/8") and were part of a rigid top structure in a
glass sided, full colony observation hive.

The metal was propolised on it's surface and the holes were plugged with
what apeared to be the same material... I had wondered if pollen had been
used to render the plugs porous so that the knew where to find then if they
wanted to unblock then.

> How large a hole can a bee propolize closed?...

I think there is a natural reaction to stuff propolis in any crack that they
can get a tongue into, but not a head. Holes larger than this can be
bridged, but I think a different mechanism is at work.

Best Regards & 73s... Dave Cushman, G8MZY
Beekeeping & Bee Breeding Website...
http://website.lineone.net/~dave.cushman