In the last few days, we’ve had well over a dozen big house flies buzzing around the house, all of a sudden. The silver lining is that they’re slower and dumber than the usual occasional summer flies, so they’re easier to swat and kill. (We live on the North Shore of Boston.)
But where the fuck are they coming from?
Coincidentally, just yesterday I had a fresh mosquito bite. On December 9 in Northern Germany, with temperatures of around 0-5° C in the last days. I blame climate change, both for your fly infection and my mosquito bite.
My next door neighbour here in the UK has a plague of flies at the moment with a few making it into my place. Like yours they are really slow and easy to swat.
She also had a strange smell coming from one of the walls so she called in ‘Roger the Rat-man’. He found a few dessicated mouse corpses in the loft and one fresh one. That was 10 days ago but the flies are still coming even though the corpse smell has gone.
How long do fly eggs take to hatch? Could the current plague be the children of a mommy and daddy fly that met at the mouse corpse 2 weeks ago?
This is a good and relevant question, if anyone happens to know the answer. We just had the pest guy out to help with our mouse problem in the cellar. He set new traps, which are all empty, and refilled the poison bait station. The latter could have led to a corpse we haven’t detected. 
For fruit flies, a cup of vinegar is a cheap and effective trap, but for other flying bugs, I have a plug-in Zevo trap, with a blue light to attract the bugs and a disposable sticky pad to hold them. I like it because it’s passive and works all day and night. I don’t like the light at night in the bathroom so I would unplug it when I went to bed. And now I’ve moved it to the kitchen.
We had a rat problem for several years. We could often hear them in the walls and ceiling areas. An eruption on large black (and slow) flies in the house was not uncommon (probably happened two or three times a year). When we finally tore down the walls the builders discovered 18 rat mummies. Extremely gross.
Yep. I’ll go with hidden animal corpse inside. A friend has a cabin in the mountains and occasionally has a fly bloom, even in winter. Animal crawls into warm space and dies. It’s the only plausible explanation.
Thanks for reminding me. I have a couple of them that I’ll redeploy.
we just used a vacuum cleaner.
For me, a sudden influx of flies always means there is a mouse liquifying somewhere in the house.
Especially if they are those iridescent green flies.
I’m not looking forward to telling my wife that this may be what is causing it. At least there’s no obvious smell in the cellar (or elsewhere) at the moment. We’ve had that happen, until I was able to find the corpse.
I have 2 of those~I am impressed with how well they work and yes, how low maintenance and passive yet effective they are. Well worth the initial start up costs.
However, be wary of the imposters-similar but cheaper units aren’t nearly as effective and not worth the few bucks saved. Zevo brand only. I’ve got one in the bathroom (I like it as a nightlight) and one in the kitchen.
You’re unlike me; I hate the light in the bathroom at night.
The only time I had an outbreak of large houseflies, I much later found a dead bird under my bed (thanks a lot, cat!).
Per Google AI:
You can try hanging some of these fly traps outside around your house:
They work great. They have a smell that’s too strong for indoors. Hang them outside in a few places and they may attract the flies into the trap before they get into your house.
Yep. Gonna be a pest like critter that went to his maker.
I wonder how people murder someone and just build a wall around them.
Our delicate noses can smell a itty bitty mouse all the way down in the cellar.
Can you imagine a whole human body decomposing in the walls.
Let me tell you about this bullfrog that decided to off himself in my smallish shed…nah, it’s just too gross to describe the aroma.
I would get mice once in a while, mostly when winter was getting really cold. It was a very old house, no way to completely keep them out. But I had a cat, and used snap traps, so I didn’t get flies.
I live in the Raleigh area of NC and we’ve had quite a few stink bugs (technically, brown marmorated stink bugs) show up in the last few months. Like moths, they like to fly around the ceiling light, finally landing somewhere long enough for me to take care of them.
The weird part is that they come one at a time. It’s like the Crow warriors in Jeremiah Johnson…they must consider it dishonorable to come in force. I’ll dispatch one and then, an hour later, there will be exactly one more flying around. I literally never see two at a time.