u/sassyourmess

I’m new to mason bees and this morning some of them hatched! When I was outside by their house, one of the landed on my hand and pooped on it? They’re so cute but what is this that they put on my had? First photo is undisturbed and second photo I swabbed it to see better.

I was seeing up my bee house yesterday and found these in new nesting material I bought from the garden store. Are these mason bees? Why are there yellow things?