Flies of Iowa

Flies are a large group of Iowa's insects, and there are a huge number of Iowa's flies which are essentially unknown. I don't know of a list of Iowa's flies, but I would guess there to be between 2,500 to 3,500 species of flies in Iowa.

Flies have a tremendous variety of habits and life cycles, some of which are well known and some of which are highly specialized and oftentimes unknown.

Flies also range the spectrum from pest and nuisance species to species that are beneficial to man because they pollinate plants, species that are beneficial to man because they prey on pest species and species that are beneficial to man because they promote decomposition of dead animals and animal waste. There are many that do not fit any of those categories, either.

I admit that I find many species of flies to be entertaining. Some are very beautiful as well. But then there are some that need to be swatted.

The photo on the top right is a commonly called a hoverfly. It belongs to the family Syrphidae, so it is often called a syrphid. Flies in this group often resemble bees or wasps, and are important pollinators of flowers. Not only that, the larvae of many of these species, including this one, are predators of aphids. This species is apparently Toxomerus marginatus.

The fly on the left is a robber fly, probably in the genus Cerotainia. With the photographs I have of the species I am not able to narrow it down to the species level. It was perched on the stalk of a weed, and it would fly out on a flight of a few inches, then it would fly back to its perch. I did not notice the small prey insect that it had captured until I saw the photographs. Robber flies are important predators in the adult phase of their lives, and probably in the larval phase as well, although the life cycle of most species is unknown.