Unwelcome visitors

[PetePontoValentino]

The next little challenge in our renovation project relates to some unwanted visitors.

We have a surplus of flies in one (and only one) of our rooms. They seem to arrive here and mostly die. We can hoover up hundreds of carcasses at a time only to find a similar number within a few hours. We also have some (about 20) strange brown marks on the walls (see photo). There are a bunch of these on the walls and ceiling, again, only in the room with the flies.

The walls are solid (60+ cm stone), the ceiling is lath and plaster (all very old).

Does anyone have an idea of what is going on here?

Pete

 

[adidat]

Living next to a farm they are a bad part of country living. That mark could be a concentrate of fly dung! If you look closely they leave about 20 small dots of it everywhere and it's fairly resilient to cleaning...

Adidat

 

[Robin Whitfield]

The mark definitely looks like fly excrement but a far more concentrated patch than Ive ever seen before!

Firstly I think I'd be looking to get rid of those patches (sugar soap/a white vinegar solution and some elbow grease) and then as it's only in one room I'd be a little concerned about what the flies are living on and where they're coming from. If they're small (gnats) then it could be a sign of rot somewhere.

 

[profchris]

They might be cluster flies, which come in as a gang from outside to hibernate.

This link seems to have useful information:

https://www.charnwood.gov.uk/files/documents/cluster_flies/Cluster Flies.pdf

 

[StevieB]

Have you checked the chimney for dead bodies?

 

[profchris]

Have you checked the chimney for dead bodies?

Good point, though with luck not human bodies. I have a disused chimney previously used for an oil-fired Aga and have twice had to remove pigeon corpses from it during the summer - crazed with avian lust, they swoon and fall in (or so I guess). One of those would generate a fine crop of flies.

 

[PetePontoValentino]

Have you checked the chimney for dead bodies?

We only found three so nothing to excessive.

We had them swept a couple of months ago...

 

[PetePontoValentino]

They might be cluster flies, which come in as a gang from outside to hibernate.

This link seems to have useful information:

https://www.charnwood.gov.uk/files/documents/cluster_flies/Cluster Flies.pdf

Thanks profchris, the PDF pretty well describes exactly what we're seeing. I know it's a bit late but we will light some citronella today and see if it deters new additions.

 

[okeydokey]

I think they are cluster flies, I have them in an attic room every year - have failed to find a way of stopping their return.

 

[PetePontoValentino]

We have finally got to the point of doing some proper work on the "fly room". we have removed the ceiling and didn't find a corpse. There was the remnants of some nest or other. Lots of vegetation and empt chestnut / walnut shells. We will do the other rooms on the top floor in the next few days.

On the more interesting side we did find some hand written documents up there too. One looks like a bill, the other is an official looking document from what was the local planning department some years ago. Both are dated 1928! Copies are attached.

 

[Just4Fun]

On the more interesting side we did find some hand written documents up there too.

When I put a new false ceiling in my home office I got my son (aged 8 or 9 at the time) to write a "letter to the future" which I put up there in an inaccessible spot. The letter cannot be retrieved before someone removes the false ceiling, which is likely to be many years away if ever. My son found it interesting to do and it might provide some amusement for whoever finds it. I don't know what he wrote - or even what language he wrote it in.

 

[clogs]

we used to have em just in our Gite in France, the only room infected.....
aparently the adults lay the eggs in the roof and they just find the smallest hole to get thru.....
the bodies were always by a glazed door.....
in the end we just left the door open once the flies started appearing.....it was only a couple of weeks.....
low crime rate and on a farm in the boonies....
spent hours with decorating caulk filling up cracks etc.....
the brown stuff is def ****......

 

[PetePontoValentino]

When I put a new false ceiling in my home office I got my son (aged 8 or 9 at the time) to write a "letter to the future" which I put up there in an inaccessible spot. The letter cannot be retrieved before someone removes the false ceiling, which is likely to be many years away if ever. My son found it interesting to do and it might provide some amusement for whoever finds it. I don't know what he wrote - or even what language he wrote it in.

We're going to do the same. copies of our finds together with some stuff from our time looking after the house!

 

[gcusick]

They certainly look like cluster flies, which are a (variable) feature of rural living. They are a pest, but actually harmless.

The flies lay eggs in the ground, where the larvae emerge and develop into flies, which then leave, typically in early autumn, and search out somewhere to hibernate. They like warm, dark spaces such as the gaps in window frames - we have Velux windows that must be the cluster fly Ritz. A single fly that finds a des res will emit a pheromone that attracts his friends and relations.

The general view is that you can’t eliminate them, but you can control the numbers. We have adopted a method of control that we use every September, before most of the flies hibernate. This involves spraying the closing surfaces of all the windows with a persistent insecticide, and treating the roofspace with a single-release aerosol. Seems to work reasonably well, avoiding mass infestations. We still need to hoover up the corpses though.

We get the insecticides from Cluster Flies | Cluster Fly Killer Treatments from ClusterFlies.co.uk | Cluster Fly Products