Sunday 10 August 2014

Propolis, plant resin collected by bees.

We all know that bees collect nectar and pollen, but did you also know that bees collect plant resin to use as a disinfectant, glue and varnish inside the hive?  This substance, called ‘Propolis’, is collected by the bees from sticky buds and tree wounds.  The bees bring it back to the hive in the same way that they  carry pollen, in the ‘pollen baskets’ on their back legs.  The only difference is that it is so sticky that they cannot unload themselves and instead, another bee has to nibble the propolis off.
Bees don’t really store propolis, but use it immediately for a number of uses.   The most annoying use for the beekeeper is that they will block any cracks with propolis.  This explains why we need a metal lever (the ‘hive tool’) to separate the parts of the hive.  The bees have glued it all together with propolis, and we have to break the joint by levering.  The propolis ‘bee glue’ can be so strong that wooden parts of the hive can come apart or break before the glue gives way!

The bees also use propolis as a disinfectant ‘varnish’ over all the internal surfaces of the hive. This protects the colony from any infective organisms that may be in the surface of the wood. 

To reduce the risk of infection, bees will also use propolis to ‘embalm’  anything that dies in the hive and is too big to drag out.  I found the object in the photo in the bottom of the brood chamber of one of my hives this spring.  I imagine it must have been there all winter.  The object is a propolised hornet.  The bees must have killed it in the hive. They probably formed a ball of bees around it and raised their temperature until the hornet died from the heat.

Propolised Hornet found in a beehive
The dead hornet was too big for the bees to drag out, so they have nibbled off all the small and thin bits like the wings and the feet.  The rest of the carcase has been covered with a layer of antiseptic propolis so that it will not rot in the hive. 

Although I don’t collect it, propolis has been used since Roman times (Pliny the Elder wrote about it) as a medicine and antiseptic.  It is still sold, dissolved in alcohol, as ‘Tincture of Propolis’ and is recommended for sore throats.

Propolis was also reputed to be one of the ingredients that made the varnish that Stradivarius used on the violins that he made.