The film which forms on the sides of a bottle of good old port. This film, broken up into small pieces, looks like the wings of bees. A port drinker is very particular not to “break the beeswing” by shaking the bottle, or turning it the wrong way up.
Beeswinged port is old port which has formed its second crust or beeswing.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894