Some of the most conspicuous insects at the Fen last weekend were bees and ants. In the recently burned over areas, the ant mounds become very visible. The ants, of course, were largely unharmed by the fire because they are safely underground. In a prairie fire, the soil temperature changes little just a couple of centimeters below the surface.
I'm pretty sure that these ants are in the genus Formica. They were very active in the warm temperatures on Saturday.
Meanwhile, willows are producing abundant pollen at the moment. The bees really like it. There were hundreds of bees from several species all over this black willow, though they were hard to photograph.