Propolis is a sticky substance produced by the bees, made primarily from tree resin which they gather all year round, but especially in spring when the sap is more readily available. It also contains wax and pollen, and various aromatic compounds and other plant nutrients which make it a useful hive product for both us and the bees. This article shows the benefits, and how and why we should encourage our colonies to propolise.
Bees need to live in an enclosed space to protect the warmth and humidity for the all important brood, and prevent intruders from entering the hive. However, they need an element of ventilation, and need to keep the interior of the hive waterproof. This is where propolis comes in, as it does the job of sealing the hive but still allowing air to permeate, and thanks to its antimicrobial action, keeps the hive clean and free from disease too.
In the previous post, we saw that the hive components were stacked together, but not fixed in place. The bees will do this with propolis, and it is a useful guide as to whether we should go in to our bees or not: if the propolis seal between the boxes cracks as we lever the crownboard off, it is really too cold to disturb them. If, however, the propolis stretches like toffee, then it is warm enough to have a look inside.
Propolis takes energy to gather and produce, so bees will rob it (as they do with honey) from another hive where they can. Here is a clip of a bee helping herself to some from a formerly occupied hive in the apiary. Watch to the end to see her scrape it all off her mandibles and with a quick flick of her middle leg, stick the wad of propolis on to her corbicula: