Large black flies suddenly and mysteriously appearing in bathroom

Reply

  #1  
Old 06-04-17, 02:56 PM
L
Member
Thread Starter
Join Date: Jun 2017
Location: United States
Posts: 1
Received 0 Votes on 0 Posts
Large black flies suddenly and mysteriously appearing in bathroom

Hi there,
Needing some help on a sudden fly infestation in our master bath. It's a very small room with a stand up shower, toilet and sink. It's used every day so I don't think they are coming from the drain. My husband went under the house and it is dry around the bathroom plumbing, with no signs of flies. We've owned this house for ten years and there has always been a pretty big fly problem in the backyard right outside this bathroom, but the window is rarely opened and we have never had this problem in our bathroom.

For the last several days, every few hours, several huge flies will just appear - they are clearly near the end of their life cycle and fly slowly, are easy to swat. But it's disconcerting to go in there and find like ten of them there on the walls. I'm attaching photos.
Name:  FullSizeRender.jpg
Views: 31035
Size:  20.6 KBName:  FullSizeRender (1).jpg
Views: 26831
Size:  25.9 KB
Really appreciate any advice. Thanks!
 
  #2  
Old 06-04-17, 04:50 PM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 9,713
Received 312 Votes on 281 Posts
There has to be some type of rotting organic material in the house. Do a though check. Try spaying the whole bath with a weak solution of bleach.
 
  #3  
Old 06-04-17, 05:17 PM
D
Forum Topic Moderator
Join Date: Sep 2012
Location: USA
Posts: 1,130
Received 56 Votes on 47 Posts
That's what we call "Blow Flies" down here. And I agree, those big ol' green flies are usually attracted to something rotting or stinky... things we as humans aren't attracted to.
 
  #4  
Old 06-04-17, 05:18 PM
C
Member
Join Date: May 2015
Location: USA
Posts: 3,138
Received 2 Votes on 2 Posts
I'd check the bath fan vent line to make sure the flapper that blocks the vent when the fan is off isn't stuck open with dust or lint. There is usually one right at the fan itself, and often another where the vent line exits the house.
 
  #5  
Old 06-06-17, 05:37 AM
P
Forum Topic Moderator
Join Date: Jun 2010
Posts: 1,847
Received 43 Votes on 37 Posts
I believe they are “house flies”. Do a search for their images. I’ve known of them to hatch from their pupal cases inside the wall and crawl under the baseboard to get inside. I think that they are newly hatched as opposed to the end of life cycle. Insects that hatch from pupae (egg-larva-pupa-adult) emerge fully grown.

Fly control can be difficult and sometimes unobtainable even when all sanitation and preventive measures are taken as they will still live in the soil. Earthworms are also a food source.

Spraying/injecting a crawling insect spray into cracks and crevices will kill them soon after they crawl through. If using an aerosol, use one that has a straw or injection tube on so you can spray it in and under baseboards, etc. Simply spraying on top of baseboard and such won’t be good enough.

Outdoors it may help to spray a water based insecticide where the house siding meets the foundation if that is available to you. I’d do that once a month anyway during spring-summer-fall. That’s where they would crawl into and under siding in order to complete life cycle inside the wall.

Is there an attic above this bathroom? There could be clues/evidence up there too. Hope this helps.
 
  #6  
Old 06-06-17, 05:37 AM
P
Forum Topic Moderator
Join Date: Jun 2010
Posts: 1,847
Received 43 Votes on 37 Posts
  #7  
Old 06-04-18, 11:23 AM
A
Member
Join Date: Jun 2018
Posts: 1
Received 0 Votes on 0 Posts
May be a dead mouse

Our cat brought in a mouse that got loose in the bathroom. I put out some poison and a couple days later large black flies appeared in that bathroom. I assumed they were there for the dead mouse. As you said, they are easy to kill because they move slowly. After using fly swatters and sticky strips, the flies were gone, and so was the mouse. This goes along with the others who have said the flies are looking for decomposing materials. Check for something like a dead mouse. Good luck!
 
  #8  
Old 06-04-18, 01:02 PM
P
Forum Topic Moderator
Join Date: Jun 2010
Posts: 1,847
Received 43 Votes on 37 Posts
Auburngirl: Good advice and words but be aware that this post is one year old. Not sure there is any activity here. Ironically, there is another post in here about flies.
 
  #9  
Old 10-13-19, 10:37 PM
D
Member
Join Date: Oct 2019
Posts: 1
Received 0 Votes on 0 Posts
Im having the same problem!!

I'm having this same issue. Did you figure out why and where they were coming from?
 
  #10  
Old 10-14-19, 08:02 AM
P
Forum Topic Moderator
Join Date: Jun 2010
Posts: 1,847
Received 43 Votes on 37 Posts
Hello Diamond14krt,
This thread is over a year old now with no updates.

Why don't you start a new thread describing the flies as to color, size, etc. ? Close up photos help if possible. Your geographic location can help too. What rooms do you see them in mostly or the greatest density, etc. Thanks for your interest!
 
Shadeladie voted this post useful.
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: