Last year I notided several bee flies, Bombylius major, behaving very oddly in my wooded back yard. Individuals would hover about 1 foot (30 cm) off the ground for extended periods. They would perch on the leaf litter intermittently, apparently to soak up some sun and warm up, then resume flights. At one point last year, there were half a dozen of these flies hovering in my back yard. It sure looked like behavior associated with mating. A behavioral biologist friend confirmed this, stating these were males hovering in wait for females. Despite watching them for some time, I have yet to see a mating. This year (2005), I have just started to see the same behavior. The individual in this photo alternately hovered and perched for some time, allowing fairly close approach with the camera.

I caught the same or another individual hovering that same afternoon:



See comments under that photo for more on the behavior.