Not every bee's a bee

This afternoon I saw in the garden many little bees. I call them like that but I'm not sure if it really are bees. I've tried to identify the species, but, how difficult it is to say: I failed ...;(

Perhaps someone with expertise may be willing to help me out? ... ;)



Nikon D700: f/5.6 : 1/160" : 105mm : ISO 200