These extraordinary little bees are from the Genus Eucera which is from the Tribe Eucerini.
Eucerini are known as the Long-horned bees. There are about 36 genera known.
Long-horned bees are ground dwelling bees and prefer to create nests in flat areas with little vegetation. (A good reason for not planting grass. 👍)
As you can see by the video, it is the males who have extra long antennae. While it is pretty common knowledge bees use their antennae to sense the world around them, this video shows something a little extra.
I was able to get quite a bit of footage of these two bees mating. During the session the male would use his legs to softly stroke the female's sides. During actual penetration, the female would throw her legs up and struggle to dislodge the male.
This is when the male would reach out with his extra long antennae and curl them around the female's antennae rhythmically stroking upward in what seems to be a pacifying gesture.