Propolis is a very sticky glue that bees make from tree sap. Mostly we see it as globs along the seams between boxes, used to seal out wind and weather. However, recently I saw first-hand, how they completely coat the inside walls of the boxes.
When dipping my new boxes into a water-based mineral preservative, I decided to dip a box that I had dipped a prior year. The outside of the box instantly became wet, soaking the wood with new minerals.
The inside of the box, however, instantly repelled the watery fluid. It dripped right off, leaving the inside walls totally dry. That thin, coated barrier wasn’t even visible to me, but clearly something the bees liked.
Bees are amazing. That thin layer of propolis is antibacterial and antimicrobial, helping bees to keep their home clean and healthy.
Another ways bees use propolis is to help control small hive beetles (shb). SHB can be either a secondary pest (opportunistic when bee colony population isn’t strong, but cans also be a primary pest meaning that their population can create so much havoc that the bees want to abscond. SHB lay eggs in the comb, feed on the bee bread or pollen patties. They leave a smelly, slimy mess that even the beekeeper doesn’t want to be around.
Bees will chase the shb into tight areas of the hive, like corners or edges of walls. Bees will use propolis to build walls to entrap the beetles, and then cover them over. This method is so effective that they will propolise anything they can’t carry out of the hive, even something like a dead mouse.
They collect sap from trees all year, but it can really be brought in in large amounts during the Fall when they sense a need to keep out weather. Some colonies have the genetics to produce A LOT of propolis. Sometimes it feels like I’ll break the boxes before I can get them apart. And the frames sometimes do pull apart from all the propolis they’ve uses to glue together.
Before becoming a beekeeper, I wondered why typical bee boxes were only stacked on top of each other, and why a hive tool is necessary. Now I know, it’s not a weak or flimsy setup. Bees can do or produce almost anything they need.