Hi, Ham.  Cut two 3" x 9" pieces from 1/8" hardware
cloth.  Fold each lengthwise 90 degrees to form 1 1/2
x 1 1/2 x 9 angles.  Fasten one to close the left hand
end, say, of the entrance with push pins.  Overlap the
first with the second to leave the amount of opening
desired, including zero, securing with more pins.  The
winter ventilation can be controlled as readily by the
air exit area as by the air entrance area so dispense
entirely with the standard entrance reducers.  I drill
a 3/4" hole in the top box between frames 2 and 3 just
below the rabbet and close off all other ventilation
holes.  This controls wintera ventilation just fine
and the adjustable entrance restriction serves to
protect small packages, nucs and swarms from robbing
and all colonies from yellow jackets.  Dan

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