Subterfuge and camouflage in nature: a bee-look-alike fly has a lucky escape

Wild bees are fascinating.  And some hoverflies mimic bees for protection presumably. This bee-look alike fly has a lucky escape though when it is next to a crab spider on an oxeye daisy in my garden.  Crab spiders do not make a web.  Instead they wait on a flower and ambush visiting insects especially butterflies, biting them behind the head and paralysing them with poisonous venom.