Propolis is a mixture of resins that covers the buds of leaves and flowers on many tree species.
This substance has important antibacterial and antiviral properties, so it is used by bees to cover the walls of the hive and thus prevent the multiplication of dangerous microorganisms. It is also used to block unwanted cracks, to narrow the main access opening in preparation for winter and to mummify animals that have entered the hive that are too bulky to be transported outside by the bees (moths, mice, etc.).