Fireplace blocking off help

[MadeFrom100percentPears]

Hi. I'm having a nightmare with flies and I need some advice. I'm hoping someone on here can help me. We have a lovely cast iron fireplace in the chimney breast in our bedroom.

Downstairs there is a wood burner in the living room sharing the chimney breast.

I'm having a problem with flies coming out of the chimney into the bedroom. Think they are cluster flies. I want to completely block the bedroom chimney off - do I have to lose the fireplace or can I just seal off the flue?

Does it need ventilation even if we have a fire downstairs? Seems to defeat the object.

Prepared to remove the fire and brick up the chimney breast if need be but would rather not do that. The fireplace in the bedroom is only for show - not functional or used but it is a nice piece and I'd like to keep it if I can make it airtight to keep the flies out!

It's really getting me down. Think I'm gonna have to sleep in my son's room! Meanwhile my husband has a complete phobia of flying insects so he won't even go in there to look at the fireplace.

A bird might have fallen down the chimney. We had that happen once and I think it must have landed behind the gas fire. Next door neighbour is in the building trade and he went up onto the roof and install a wire thing - I think its called a cowl- to stop them nesting on the chimney pot.

I think that too - we have booked a chimney sweep to come and check the chimney and fit a mesh at the top.

I have just gone and had a close look though and the fireplace is just covered with flies. Don't know what to do! I've contacted the pest control people and they've said I need to have them for a week before they will come.

I'm also too bloody scared to move the fireplace in case they all come swarming out at me.

Spray the room/fireplace with fly killer, repeat every few hours, then every day until they stop coming (ventilate after leaving for a few minutes each time), if it's something rotting they will finish hatching in a few days. If it's cluster flies are they getting into the chimney from the loft? Have a look up there and see if there are flies there too, if so spray them too.

Also you could tape cardboard or material (if it's an awkward shape) over the completely covering the fireplace opening to stop them getting into the room, if you don't want to spray repeatedly.

We had this and got a proper chimney sweep round, who vacuumed the chimney! There were dead birds there.
Afterwards, the flies never returned.

It is absolutely essential to have some form of ventilation to the fireplace afterwards because of condensation that builds up naturally in a room. Otherwise the moisture will build up and your health and your windows may suffer.

Thanks for the advice. I've blocked off the fireplace with bin bags and duct tape after speaking to the chimney sweep. He says he can get rid of them and put something to block it so they can't return. I'm properly rattled by it - hate creepy crawly things. Hopefully this will stop them getting into the bedroom until he can come. I'm pretty sure it is cluster fly. I'm so grossed out.

Measure the rough size of the opening and order a chimney balloon. You can block off the chimney fairly quickly and easily and can always remove it if you need to.

I looked at chimney balloon but I wasn't sure if I could use one given the chimney is shared with the downstairs log burner? Would this be safe?

Old pillows work well enough to temporarily block the chimney. Very important to remember to remove them though

Do you mean I'd have to remove them to light the fire downstairs?

Not sure if you can keep it in while you are using the other fireplace. I think it should be ok. Either way they are easy to put in and take out so you could just put it in over the summer while you are having the fly issues.