"Lack" of pollen was also noted here. Sometimes I think the rain washed it off, and I've observed the "glue" too. But I seemed to notice a preference of some lily pollen by bees, I think. I have no other explanation why I see an abundance of pollen on particular anthers in the early morning, only to return later that day to pollinate, and find absolutely no pollen left!
Of course, some anthers hardly produce pollen at all, and I have found that to be the case on certain Iris spp. especially. For those lilies that hardly produce pollen, I've wondered if what is there is viable anyway (?)
On another note, any evidence that neem helps prevent slugs?
