Flies in attic

lisa701

Ever since moving into our house 15 years ago we have had an issue with flies in the attic. They are similar size to bluebottles but they are more brown in colour.

The space was full of dust and dirt, and there were several holes in the roof and assumed that is what was causing the problem. We got the roof replaced 10 years ago and completely cleared the attic space then. There were no signs of anything untoward such as a dead bird, mice, maggots etc. so we didnt have a clue why the space was attracting flies, but thought that replacing the roof and having a good clean up would sort it out - but sadly it hasnt.

We don't use the space as much as we would like to for storage as I hate going in there. Every month or so I get him to go up and have a look and he always ends up vacuuming several dead flies off the floor so they must still be getting in somewhere.

Any ideas where these little critters are coming from and why? The place is clean, there is no dirt or dust, no signs of mice etc. so I don't understand what attracts them.

We did have two velux windows installed, but checked them and all the seals around them are fine so no way anything could get in that way.

Our only thought was the gap around the outside (think my hubby called it the eaves??). We bought a roll of stuff from Screfix which said it was to stop flies etc. getting in through the eaves but when we come to install it we found its not so easy to access the area.

Any ideas?

DaftyDuck

Look up "Cluster Flies" on Google... Are those the chaps and chapesses?

If so, they are quite a problem to get rid of, and even more revolting to keep. You can buy traps (pheromone-scented) which help, but expert prevention may be called for.

If they don't look like cluster flies, post a photo of a few corpses for us to identify...

Norman_Castle

The windows might be the cause. Instead of finding another way out they die trying to fly through the glass. Flies don't understand glass.

themull1

How many flies are there at any one time? are we talking five or fifty?

devildog

I think you will find they ARE cluster flies. You can't prevent them and experts can only come in and kill off any that are in there at the time.They will return.
You could get Pest Control out but I was advised by them to wait until a frosty day (and the flies were keeping warm in the roof) and then liberally spray with fly spray and to keep doing this every year.
They are horrible, the only 'upside' is that they re relatively 'clean' flies (not that that is any consolation)

DaftyDuck

It is difficult to control cluster flies, but it is possible. Pheromone traps help and, after a couple of years, you can be completely rid of them. They may be 'clean', but they come across to me as unbelievably 'stupid' and, combined with the sheer number of them, that makes them a real pain.

OP, let us know if they look like cluster flies from Googling and, if so, there's plenty of advice to offer.

Ebe_Scrooge

Is your house built on an ancient Indian burial plot ? Were the previous family murdered gruesomely ?

lisa701

Yes thats the vile things.

I dont go in there regularly but when I do (maybe every month or two) there can be as many as 20 dead ones on the floor.

I just don't understand where they are coming from. Surely if the place has been completely cleaned with nothing left behind they could be living in then they are coming in from elsewhere? But where?

The only opening is the eaves, the roof is completely sound, and the windows are always closed. Had someone check the seals on the windows several times and they are fine so nothing coming in that way.

Surely if I find where they are coming in and block off that route they won't be able to get in anymore?

lisa701

DaftyDuck wrote: »

It is difficult to control cluster flies, but it is possible. Pheromone traps help and, after a couple of years, you can be completely rid of them. They may be 'clean', but they come across to me as unbelievably 'stupid' and, combined with the sheer number of them, that makes them a real pain.

OP, let us know if they look like cluster flies from Googling and, if so, there's plenty of advice to offer.

Yes they are. I just cannot understand where they are coming from though. The place has been cleared out countless times with nothing left behind, so they must be coming back in from outside - but where?

DaftyDuck

You WILL NOT be able to block them out... they'll find the smallest, tiniest hole in the roof. Block them all, and your roof will explode in mould, rot and fungi.

If one (female, I think) comes in, dozens of others will follow. Once they are in, the pheromone trail builds up, and hundreds come in... and so on. They normally come in in the colder autumn so, if you've got them now, you'll need to work to get rid of them.

You can treat the attic, or you can treat the source, or both. Both is obviously better, if possible.

Firstly, it's worth looking on your Council website. Some treat cluster flies for free, and often if they do charge, it's not so huge a cost.

For DIY, never squash the flies. Never, I says, never, ever. Lingering smells and all that. Use a vacuum cleaner, and suck the bu66ers up. (When I had this in an old Vicarage attic, I bought a cheap rechargeable Black & Decker Dustbuster for the purpose). You can spray first, but it's easier to spot them if they are still alive. Get them all in one go if you possibly can, but go back every two days for a week for a further tidy-up. When you've done that, then spray to kill the very few that you haven't seen.

They will return in a few weeks, a new crop as it were. You need to keep your eyes peeled, and start clearing as soon as they arrive. The idea is to suck them up BEFORE others are attracted. (more in a mo... work coming in)

When you empty your vacuum, do so into a sealed poly bag, and chuck it in a bin... ideally one that's away from your house (Any neighbours you dislike? :eek:)

You can get insecticidal "bombs" for attics; I never like using something so powerful, but they do exist...

When the insects are relatively absent, wipe over the inside and outside of windows and air vents with a mild bleach solution - 1/10 or 1/20 will be easily strong enough. You can leave sticky fly paper up... but you'll have to remove it pronto, say every two days, or you will just exacerbate the problem.

The other thing you can do is attack the area where they have come from. It's normally within 100 - 200 yards - often much less. They are weak fliers, can't really fly upwind much, and lay their eggs in worms in grassy areas. You can treat these areas with agricultural insecticides to eliminate them at source. If it's a Council grassy area, they should do something about it if you complain. If it is likely to be your own lawn, I think the answer is to let the grass grow longer (or, helpfully, cut it shorter... my memory is failing... I'll look it up) and improve the drainage by aerating it.

It is a long business. It took me three years to eliminate them from my fairly large attics (... they were coming from the next door churchyard). I rent that house out now, and they are back, apparently, but not too bad. Yet. If left, it can be a serious problem. I do know properties that have been blighted by these for years, so it's well-worth getting on top of.

Even if you ignore it, one year they'll just... vanish..... Either the area where they come from has been ploughed/treated/changed, or there's been a cold spell when they least expected it. Or, they've just moved to your neighbour's attic.