An Apple Tree Buzzing

While spending Easter at my grandparents house I noticed their apple tree was in bloom. The fruit is a small green crabapple of some sort, not very edible at all. The flowers were being swarmed by bees though. Assorted Mason Bees were the main pollinator here. I hardly saw any Honeybees on it at all but they were there. I think they were more interested in my grandparent's flowering quinces (an Asian plant that can produce edible fruit farther south). Bumblebees were there too but they're not in as great of numbers at this time of year.