Unlike what they experience in modern, conventional beekeeping equipment, i.e. Langstroth hives, in the wild, honey bees often choose a cavity for their hive that is very rough on the inside. These rough surfaces stimulate the production of propolis which they use to coat the interior of the hive to smooth-out those rough surfaces. Langstroth hives are already smooth on the inside and so the bees rarely, if ever, coat the inside of the hive boxes with propolis.
Propolis is a natural anti-microbial substance that kills bacteria, viruses, fungi, and other microbes. The propolis coating in a hive is one of the main reasons that a honey bee hive is one of the cleanliest, most sanitary places on earth.
Because the bees do not coat the already smooth interior surfaces of Langstroth hive boxes, scientists who study honey bees are beginning to wonder if perhaps the use of Langstroth hives has contributed to the decline of honey bee health and vitality.
So, Bee Tree Hives™ have hive boxes with rough surfaces on the inside. Below is a photo of a colony installed in a Bee Tree Hive™ just a few weeks ago. You can see that they are already beginning to coat the rough surfaces with golden-brown propolis.