How has the weather been? If it's been really cold and the bees haven't been able to fly, that could just be they were cooped up too long and couldn't wait any longer to use the restroom aka: anywhere but in the hive.
If it hasn't been terribly cold and the bees have been able to cleanse you could:
Add tea tree oil to your sugar syrup (lots of recipes online), use a blender and emulsify it with lecithin to suspend it in the syrup, since oil and water don't mix otherwise.
Tea tree is naturally anti-fungal.
How to "home brew" your own Honey Bee Healthy for use as an additive to syrup when feeding your bees or as use as an alternative to smoke when working your hives. Chedk out the recipe and preparation tips.
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