Which trees are a common source of propolis?

Poplar trees are a common source of propolis due to the resins they produce. When bees collect this resin, they mix it with beeswax, pollen, and their saliva to create propolis, a substance used to seal and protect their hives. The sticky, protective qualities of propolis help to maintain hive integrity and ward off infections and pests.

The other options, while they may have resin or sap, do not provide the same quantity or quality of materials that bees prefer for propolis production. For example, many types of pines can produce resin, but it is often not as suitable for propolis as that from poplar trees, which is favored by bees for its specific chemical composition. Thus, poplar trees play a crucial role in beekeeping, contributing significantly to the health and maintenance of bee colonies through the propolis they help produce.