Propolis — "bee glue" — is a resin-and-wax cement that honey bees make by mixing collected tree and bud exudate with wax and salivary enzymes. Bees smear it over cracks, knot-holes and joints in the nest cavity, and in wild colonies often coat the entire interior in a thin "propolis envelope." This 3D cutaway shows a hive-wall gap being sealed while airborne microbes attempt to drift in through it.
Propolis has been prized since antiquity — Egyptians used it in embalming, and the name itself comes from Greek roots meaning "before the city," a nod to how bees pile it up as a defensive rampart at the entrance to their nest.
A 3D cutaway of a hive wall shows worker bees plugging a gap with resin propolis while airborne microbes drift toward the opening — some are chemically neutralised on contact, others slip through an undefended seal.
Coverage sets how much of the gap is physically filled with resin; temperature shifts propolis between brittle, workable and sagging states, changing how effectively that coverage actually seals; microbial pressure sets how many spores test the barrier per second.
Raise propolis coverage and dial the hive temperature toward its natural ~30°C working range to maximise seal integrity, then watch the neutralised/breach tally respond as microbial pressure changes. Toggle the full propolis envelope to see the interior varnish layer.
Propolis contains dozens of flavonoids and phenolic acids with genuine antibacterial and antifungal activity — it has been used in traditional medicine and modern wound dressings, and its name means "before the city," the defensive rampart bees build at their nest entrance.