Bee flies (this one is probably a Bombylius sp.) are commonly observed visiting flowers in
sand country. They are especially fond of the yellow disk flowers like this Bidens coronata, a common plant in native prairie marshes, where it grows among tussocks of blue-joint grass. This species is one of the more showy of the Bidens genus.
In this case, the fly came too close and was captured and devoured by a well-camouflaged crab spider (family Thomisidae), a non-web building, but nonetheless predatory species. Bidens species bloom
in late summer, often in seasonally flooded areas of marshes.