Extra-floral activity

Walking home along the hedgerow the other day I was distracted by a deep humming sound. Being prime swarm season for honeybees, I got excited and thought I might finally be about to witness my first swarm. I wasn’t in luck with the swarm but quickly realised that the entire length of the hedgerow was humming? This seemed strange because there were few bees on the wildflowers and there was nothing flowering in the hedge. Why were all these bees here? I climbed up to take a closer look.

 

When I looked into the hedge I found it was full of honeybees, bumblebees and many species of fly. The hum from inside was incredible and based on the number of honeybees I could see in one section, I estimated that there must have been 400+ bees along the 30-40 metre hedge. The bees were walking around the leaves with their tongues out like this one …

honeybee tongue on cherry laurel
I was puzzled. With no obvious source of pollen or nectar from flowers what were they all doing in there? The strangest thing is that even though I walk past the same hedge everyday, I have only experienced this phenomenon on one occasion.

The hedge is a cherry laurel [Prunus laurocerasus] and with research, I found lots of information from beekeepers about how popular the plant is as a source of nectar for honeybees. It turns out that the plant releases nectar through glands on the underside of its leaves called ‘extra-floral nectaries’. Apparently Willow, Bracken and Field beans do the same so keep an eye and an ear out. It explains why the bees were licking the leaves in the way they were. But this is not for pollination so what is the plant getting in return for giving away its nectar to the bees?

I found a theory that the plant releases nectar in this way as a defence mechanism against pests. A plant under attack from pests might give off nectar from its leaves to attract predatory insects like flies, ladybirds and wasps who will feast on the nectar but also gorge on any small plant-eating types [rather clever]. There was some visible damage to the leaves [like in the photo below] so it might make sense that the plant took some defensive measures.

damaged leaves
Based on this plant defence theory, it strikes me that the bees are getting a free lunch feasting on the cherry laurel nectar because to my knowledge I don’t think bees eat other insects? Natural communities are packed full of beneficial relationships and it makes me wonder whether there is a role for the bees here that we do not yet understand. Or perhaps there is such a thing as a free lunch in nature and the cherry laurel simply releases its nectar to the bees out of pure pleasure : )

Bees and plants have been working together in this way for the last 100 million years [the oldest honeybee fossil was found in Burma in 2006] and as a result, have built highly sophisticated relationships. Modern humans have had about 200,000 years to develop our communities. I think there is so much we humans can learn from observing the beneficial relationships that exist naturally around us, particularly in these times of worrying political shift and economic over-dependence.

bee bum in cherry laurel
I feel lucky to have been walking past the cherry laurel hedge when it decided to engage its extra floral nectaries and fill itself with bees. It’s given me another little glimpse into the complex relationship bees have with their environment and its also a reminder of how important our hedgerows are for bees and biodiversity in amongst our monoculture landscape.