Bees collect propolis as a resinous plant gum from tree buds. They use it as a glue to plug unwanted holes in the hive and to polish the inside of brood cells. Propolis has anti-bacterial and anti-fungal properties.
Propolis is carried on the back legs to bring back to the colony or to move it around within the hive.
It is claimed to have health benefits for people and is sold in shops in a range of preparations including lozenges and ointments. Propolis is claimed to be effective in treating a number of ailments and disorders.
Propolis is also used by bees to embalm larger creatures that die inside the hive and cannot be removed (such as mice). It is sticky at low temperatures and brittle when cold.