Studies have shown that areas where mistletoe has been cleared have a significant decrease in the populations of birds and other species.
Then:
It’s not all about wild animals either. There is evidence suggesting some mistletoe species have value in the treatment of cancer - it’s been used for this since the 1920s. The theory is that mistletoe therapy reduces the side effects of chemotherapy, improving quality of life and helping patients better tolerate the treatment.
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From mythology The Golden Bough/Balder and the Mistletoe
The Golden Bough/Balder and the Mistletoe - Wikisource, the free online library
Not too late:
it may be the reason why in the north of England they say that if you wish your dairy to thrive you should give your bunch of mistletoe to the first cow that calves after New Year’s Day, for it is well known that nothing is so fatal to milk and butter as witchcraft. Similarly in Wales, for the sake of ensuring good luck to the dairy, people used to give a branch of mistletoe to the first cow that gave birth to a calf after the first hour of the New Year; and in rural districts of Wales, where mistletoe abounded, there was always a profusion of it in the farmhouses. When mistletoe was scarce, Welsh farmers used to say, “No mistletoe, no luck”; but if there was a fine crop of mistletoe, they expected a fine crop of corn