"(mycelia is underground invisible part of fungus, like roots of a plant; I wonder how one, at all, can see this -- bees sucking mycellium?..)"
Your analogy proves your lack of knowledge of fungi, since it is absolutely wrong. The Mycelia is more akin to the Plant, what grows above ground is just a Fruit at the end of their growth cycle. It is the most ephemeral part of a fungi.
The mycelial network is actually the true living organism.
How can one see Bees sucking at mycelium? Well if you ever had grown a mushroom patch in your own garden, you would know that the mycelia extends to just below the surface of the soil, bees will push aside any loose soil to get at those fine root tips, which you can then observe them sucking at.
RE: Sacred Bee Medicine