Spiders eat bees

Hello Margriet.
This is my second year with a mason bee nest. When I cracked
open my corn plastic stack to clean my nest last year I was surprised to find two
of the tunnels occupied by spiders.
I had at least 25 cocoons hatch this spring. I went out o check on the house
on Tuesday and noticed webs around the house. On closer inspection, at least
three tunnels had fine webs over the openings.
I assume the spiders prey on the bees. Am I correct? And if so, how do I get
rid of them without disturbing the entire corn plastic bee stack?

Thanks,

Kevin K
That is a good question.  The only way I know is to catch and remove them from the site.  This would be quite difficult I think. 
 I have seen a jumping spider catch a mason bee!  So bees beware!