|Greater Bee Fly Bombylius major (photo taken in my yard)
Bee Flies (Family Bombyliidae) are very common right about now. These fat-bodied bee mimics are very hairy and have a stiff-looking proboscis, but are true flies (having only 2 wings). They get a measure of protection by looking like bees, and even hovering and buzzing like them on occasion, but cannot sting. They are are very good pollinators in their own right though as well.
One of the most common and widespread (being found in Europe and Asia as well as most of North America) is the Greater Bee Fly. It is sometimes also called the Large, or Black-tailed Bee Fly. The dark patches on their wings are usually good field marks for identifying them. They can be extremely common along woodland edges and wherever there are spring wildflowers.
I think it is ironic that bee flies are bee mimics. Many of them, including the one pictured, are parasatoids of solitary mining bees (mostly in the genus Andrena). They lay their eggs at the entrance of the mother bee's tunnel, sometimes even flicking the eggs deftly down the hole itself. The hatching maggots eats the bee larvae and then the food stores that the mother had provided. So they not only look like bees, but feed on them and their food provisions when they are young as well.
So next time you think you see a bee this time of year, take a second look. It might actually be a bee fly, looking for food for itself or a bee hole for its young.