Dear Readers, I need to tell you a quick story about this book,’Trees’ by Peter A. Thomas, which arrived while I was in Canada. The courier left it behind the wheelie bins (which is where he usually leaves them), but it wasn’t there when we returned. However, it was eventually found, still in its cardboard wrapping, in the side return to the house – a fox had clearly found it, dragged it under the whole in the back gate, and had been munching on it before deciding that it wasn’t edible. If my husband hadn’t been watering the garden (and since then we’ve had rain every day but that’s another story) I would never have found it. Fortunately the book itself was intact, and just as well, because it’s an absolute delight, and a fine addition to the teetering pile on my bedside story. I haven’t read enough to actually review it yet, but I thought that I would just share one piece of information that I’ve gleaned by opening it randomly.
There has long been a mystery about the relationship between bumblebees and lime trees. The lime trees provide abundant nectar for a very long period, and so they are beloved by pollinators of all kinds. I well remember sitting under a lime tree when I went to visit my parents in Dorchester, and almost being lulled to sleep by the sweet, heavy perfume. However, towards the end of the season great heaps of dead bumblebees have been found under the lime trees, particularly Silver Lime (Tilia tomentosa) and Caucasian Lime (Tilia x euchlora).
At first, it was thought that the nectar might be somehow poisoning the bees. Then, it was thought that the nectar might contain mannose, a sugar which is largely indigestible by bees. But then, it was noticed that the dead bees contained very few honeybees, and this was a clue. Honeybees will visit a plant or not depending on its nectar abundance, whereas bumblebees seem to return again and again to a site that once had nectar. So, as the year wore on and there was less nectar (especially in a dry year), the honeybees looked elsewhere, but the bumblebees seemed to be addicted to their lime tree, even when it didn’t provide them with enough food. Furthermore, the nectar of lime trees contains caffeine – could this have helped the bumblebees to become dependent? I know I ‘need’ my morning coffee, so perhaps it has a similar effect on our small furry flying relatives. At any rate, the mystery is not yet solved, but the hypothesis is that the bumblebees are not in any way poisoned, but simply starve to death. Fascinating stuff (to me at least), and I look forward to finding out what other things this book has to teach me, so that I can share them with you all.
Photo One by By Jean-Pol GRANDMONT – Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=2788202
Photo Two byIvar Leidus (Own work) via Wikimedia Commons