How does bees make propolis?

When a tree is damaged or its bark cut, a resin or sap floods the damaged area to protect the tree from bacteria or fungi attacking it. You might have noticed this sticky substance on a tree trunk. Bees cottoned on to this and started to collect the tree sap, just as they collect pollen and nectar. They add saliva and beeswax to the sap to prepare it for use in the beehive, creating a nutrient rich product called propolis.

Once back at the hive, the bees use propolis like Polyfilla or “bee-glue” to seal the beehive closed and create a highly protective layer – helping the hive to stay sterile. In very real terms, propolis functions as the natural defence and immune system of the beehive.