Propolis is a resinous material gathered by bees from the leaf buds and bark of trees, especially poplars, birch and conifers. In the hive bees mix propolis with wax and use it for repair and construction in the hive, as well as for insulation and protection. Propolis also contains small amounts of pollen and other bee materials. The bees use propolis to protect the hive against bacteria or viral infection and dangerous toxins. Beehives are a virtually sterile atmosphere due to the use of Propolis by the bees.