Propolis, or bee glue, is a resinous mixture that honey bees produce by mixing saliva and beeswax with exudate gathered from tree buds, sap flows, or other botanical sources. The chemical composition and nature of propolis depend on environmental conditions and harvested resources. Honey bees are opportunists, gathering what they need from available sources, and detailed analyses show that the chemical composition of propolis varies considerably from region to region, along with the vegetation. Bees seal the beehive with propolis to protect the colony from the elements, such as rain and cold winter drafts.
Propolis functions may include:
Reinforcement of structural stability and reduced vibration.
Improved thermal insulation to the hive and reduced water loss.
Protection from pathogens, via anti-fungal and antibacterial properties.
Bees comprise of eusocial colonies, the highest level of organization of sociality and are characterized by cooperative brood care, (including care of offspring from other individuals), and a division of labour of overlapping generations. The bee is considered a superorganism, a social unit where division of labour is highly specialised and where individuals are not able to survive by themselves for extended periods. A superorganism can be defined as "a collection of agents which can act in concert to produce phenomena governed by the collective”.