Are small flies invading your home right now? Here's what it could be. 

SOUTH BEND, Ind. --  Have you been noticing an influx of small, annoying flying insects in your home recently?
Mark VanderWerp is a board-certified entomologist and Manager of Education and Training for Rose Pest Solutions. He’s based in the Detroit area. VanderWerp explained what kind of insects people may be seeing right now.
“In the fall, there are a couple of things that tend to enter. There's one group of pests that we call overwintering pests, and some of those include flies.

So, if you've ever heard of a cluster fly, they look a lot like your typical trash kind of fly. Looks like a house fly, you know, medium-sized, gray, nothing particularly remarkable about them, but they don't come out of trash,” said VanderWerp. He says these flies come inside to find a place to spend the winter.

VandenWerp says there are so many different types of flies, but pinpointed a handful of small ones that are common house pests.
He says the big one this time of year is the vinegar fly, or small fruit flies.

“These are kind of the bane of the average homeowner's kitchen. They'll buzz around fresh fruit out on the counter. They'll buzz around trash. They'll buzz around, you know, wet sponges and that kind of thing around the sink. There's different species of these things, and they can behave a little differently.

So, there's some that we call dark-eyed vinegar flies, and those ones are a little bit gnarlier. So those things really do come out of advanced decay kinds of things. So if you’ve got gunk in your drain, or if you're having some kind of septic issue, those might turn up,” said VanderWerp. “A bunch of the other ones just come out of produce, that kind of thing. So you buy a bag of potatoes at the store, or you get some raspberries. You bring them home, and then these flies can actually hitch a ride in those and start emerging in your kitchen.”

He says the really common ones are called red-eyed vinegar flies. He describes them as very small with striped bodies and red eyes. He says they can come from outside, sometimes through window screens.

He says there is also an invasive species of this red-eyed vinegar fly with spotted wings that can come from fruit at the grocery store, called the spotted wing drosophila. So why are we seeing so many of these pesky flies right now?

“This time of year, it particularly explodes, because you have a lot of harvest going on. So, you have, you know, peaches, apples, pumpkins, squash, all kinds of things ripe right now. If you live near a farm, or if you grow some stuff on your own property, or if you live next to someone who has an ornamental pear tree or a crab apple tree, you know, there's probably rotting fruit in the ground right now, pretty close to where you live, and that's what these things thrive on,” said VanderWerp.

He says wind can also cause them to spread further, since they are small and aren’t great fliers.
VanderWerp says populations build up throughout the year, and some overwinter, but a lot don't make it because winter is tough on bugs.
He also discussed other types of flies you may see in your home, like drain flies, which are sometimes called moth flies, and phorid flies.

He says if you're seeing drain flies in your home, it is likely an indication of a plumbing issue.
“There's a couple of different things people call drain flies. One of them, they look like little moths, and they're sometimes called moth flies. If you smush them, they leave a little smudge, kind of like a moth. I think that's partially how they get the name. So that is what we would traditionally call a drain fly. They're not strong fliers. They just kind of sit on the wall. If you've ever been to a public restroom, you've probably seen those little black or grayish, moth-y looking things sitting on the wall,” said Vanderwerp.

“Typically, those come out of advanced decay gunk down in drains, or if you have a floor drain that's dried out. So you know, there's gobs of these things down in the sewer system. This is why we put water in our drains, so bugs can't fly up out of the sewer system into your home.”
Phorid flies are another type of fly VanderWerp talked about. He says their diet is similar to that of a drain fly.
“Their diets are quite disgusting. Again, they can come out of dried-out drains, but they can also come out if there's a septic leak or a sanitation line break under the slab of a structure; they will actually feed on that gunk that gets down in the soil. And again, there can be just epic populations of these things that bust out,” said VanderWerp.

“These things you're going to tend to see mid-summer, late summer, because that's when they're going through their life cycle the fastest. And so, if anyone has these kind of persistent, small flies that won't go away, there's clouds of them, can't figure out where they're coming from, they've called a couple companies, no one knows where they're coming from-- that's probably Phorid flies, and it may in fact be an issue below the structure where the sanitation lines have ruptured and drained some pretty nasty stuff into the soil that these things are breeding on.”

VanderWerp says identifying flies correctly can be very difficult, but some websites can give a general ID for flies. He also created a video about identifying flies that you can watch here. When it comes to apple cider vinegar-based traps, he says it might work for some flies, but not others.

“It does work pretty well with those red-eyed vinegar flies. We're talking about the small fruit flies. But again, yeah, what attractant you use really depends on the fly. So, you know, when you're using things like apple cider vinegar, that is the kind of smell of like newly decayed fruit, and so some of those things love that,” said VanderWerp.

“That's not going to work in the drain flies. It's not going to work in Phorid flies because they're not into that. It's too fresh. They want it to be really nasty before they go after it. So yeah, you do have to use an appropriate bait, depending on the fly you're trying to trap. Some of the baits you wouldn't want to put in a cup and set it on your counter.”

VanderWerp says there are other things you can use besides bait to trap flies, like light traps with glue boards. He says that works really well for most of these flies, and really well against vinegar flies and phorid flies

.
He says you can also use sticky paper. If you know how they are getting in, you may be able to use sealant or find a finer window screen.
According to VanderWerp, your solution needs to be tailored to the type of fly you have. If you don't know, that's when he says it's time to get help by calling a pest management company or university extension to get more information.

Debbie lives in Osceola and says every year they get some of these flies, but this year they are everywhere.
“Of course, they're in the kitchen. Most of them are in the kitchen. So now I'm covering everything, and it's really annoying, you know, especially every time we put some food down, you’ve got to make sure you cover it,” said Debbie. “The first time I really noticed it. I had a salad out, and it came from a restaurant, so it was covered. When I opened it, the salad took off. Kind of it was just so filled with these little things.”
She says she’s tried everything, including bug spray, sticky paper, light traps, and even an apple cider vinegar solution.