Hosenbiene (kind of sand bee)

You're right. the "Hosenbiene" looks much more like it. Great thanks for your help. And now I'm looking for the English name.

I´ve only found the german name - in switzerland is this bee near extinction, germany it is rare.

it is a solitary living bee, it is making a nest

I haven't seen this often. I wonder what he is constructing?

:))

Thanks. this brought me on the right track I think.

it is an Andrena sp. for sure - I don´t know which one...