Propolis or
bee glue is a resinous mixture that
honey bees collect from tree buds, sap flows, or other botanical sources. It is used as a sealant for unwanted open spaces in the
hive. Propolis is used for small gaps (approximately or less), while larger spaces are usually filled with
beeswax. Its color varies depending on its botanical source, the most common being dark
brown. Propolis is sticky at and above room temperature, . At lower temperatures, it becomes hard and very brittle.