Bee for is and explanation please

[laetoli]

Hi, I was merrily snapping the bee in the first picture when it was dive-bombed by another, different-looking bee as shown in the second picture. Subsequently, they both flew off. Is the second bee a male of the same species that the first is a female of and making amorous introductions? Please could someone id these bees for me and explain what is going on.
Take care,
Paul

[Matt Smith]

Your first bee is a Colletes sp. Not sure about the second bee, though the slightly boxy abdoiminal shape suggests a Megachilid of some site. Male bees often "pounce" on other bees "just in case", I would say this is a case of mistaken identitiy.

[laetoli]

Thanks Matt. So it's not just me who gets confused as to who's what when it comes to bees ... it's the bees themselves!
Best wishes,
Paul