Don't know about the flies.....certainly not typical of most gardens.....do you have a neighbor with a poorly covered garbage can or someone who uses fresh manure to fertilize?
The floppyness is likely due to the drought....but they do tend to flop a bit in the best of circumstances....
You can move them in the early fall....water will before....prepare a spot and keep watered well into winter.....and take a good shovelfull of soil when you dig them.
Linda C

Thanks Linda. We're in the city, so our small yard is not far from the garbage/alley, but the garbage is usually covered. I thought flies prefered garbage to flowers? They hang out on the tops of the flowers--just sit there (maybe they're too hot to fly :). And when I go to water or look closely at the plants, they buzz around & start biting.

Thanks for the advice on the other 2 questions!

Even though the garbage is covered.....flies can still smell it and gather.....finding it covered they go to something else that smells sweet and/or moist.
Linda C

The flies that hang out in garbage cans are usually one of the flies considered filth flies & would have lapping or sucking, but not piercing mouth parts. Here in Michigan, I'm often bothered in the garden by stable flies or dog flies (not deer or horse flies). These are a fly about the size of a house fly (a little smaller) and they have piercing mouth parts & inflict painful bites. For some reason, they seem most active when it's humid out. They are strong fliers (can arrive from long distances) & able to home in on the CO2 emissions in our breath. It's not likely they would feed on garbage unless there's blood in the offing. If they're a garden pest here in metro Bay City, they're likely to be a pest in your little town. BTW, what street is Chicago on? ;o)

The first photo in the link I provide below shows a good pic of a stable fly about to dine on a hairy human drumstick.

Al

Here is a link that might be useful: C'mon! Let's go see what stable flies look like.