Extension Educator, Horticulture
Where there are people; there are flies. It's not so much that they love us. They love all the stuff that goes with us such as garbage, food, and grass clippings. To be fair not all flies are bad neighbors. Some are beneficial to us since they are predators and parasitoids of pest insects. For instance robber flies are predators often found hanging out on flowering plants. As lions hanging out at the watering hole for the wildebeests, robber flies wait to abduct a tasty insect attracted to the flowers. Robber flies are impressive with their really long legs compared to their body size, large bulging eyes, and a triangular face. Robber fly larvae are also beneficial since they feed on soil grubs or grasshopper eggs.
Pest flies are hard to forget such as the ubiquitous house fly; easily identified by their gray color and 4 black lines on their back. Flies are not particular where they hang out. House flies love pretty much any kind of rotting organic stuff such as dead animals, food garbage or excrement. They particularly love horse manure, even more than stable flies. Now for the "gross alert". If you are eating a meal right now, consider yourself warned that I will be delving into gross-but-true information. You may want to finish your meal before continuing. Or you may want to call in a kid and read it to them. They love gross stuff.
The female house fly lays her eggs on rotting organic stuff. Each female can lay up to 600 eggs. Within 12 to 24 hours the eggs develop into white legless maggots. If the right conditions exist, the maggots become flies in as little as 2 weeks. That's a lot of flies in a very short period of time. Have the kid do the math for the possible yearly accumulation of flies.
If house flies kept to garbage they would be a nuisance for sure, but these flies go a little further on the gross meter. House fly mouthparts work like a sponge; therefore they require liquid food. When they find something yummy that is not liquid such as your sandwich, they don't let it stop them. They regurgitate their saliva on the food then proceed to use their sponge to soak up a meal. Unfortunately their saliva contains remnants of their last meal, which may have been at the local horse barn, garbage can or roadkill. This is your cue to yell "GROSS". House flies have been linked to spreading all kinds of nasty diseases.
Stable flies have a name they don't deserve. It doesn't describe their psychological state as far as I know and they aren't found only in stables. Stable flies are one of the biting flies that love your tasty ankles. The maggots live in rotting vegetation such as grass clippings.
Deer flies also bite any warm body that moves. Why does their bite hurt so much? Imagine mosquito mouthparts as a hypodermic needle and biting fly mouthparts as a giant dagger. Deer flies are a little bigger than house flies but with dark markings on their clear wings usually noticed as you scream and smash the bugger. Deer flies find human faces and necks particularly appealing, sometimes attacking in swarms of four to five at one time. I have had to run down hiking trails to get away from them. On trails they always seem to attack the first person in the line. Sometimes it pays to be last.
Sanitation is key in reducing fly populations. With all the recent rains there is plenty of decaying vegetation so control can be difficult. Insect repellants, long sleeved shirts, long pants, and a hat can help to keep the biters away. They bring a whole new meaning to "shoo fly".