Cluster flies belong to a family of flies called Pollenia and are medium sized, about 10mm in length. They are greyish olive in colour and adorned with golden hairs which makes them quite distinctive to the trained eye.
They start to appear in our homes in the Autumn months and become active again in the Spring or in an exceptional Winter warm spell. If you are lucky you may be totally oblivious of their invasion into your home.
How can you stop them entering your home?
It is very difficult to stop their invasion as you most likely will be unaware that it is happening.
On warm Autumn days they like to gather on south facing walls, from here they make their way upwards and enter into your attic through any gap in the eaves. You can try and block any obvious gaps in the area of your eaves, but it is difficult to totally restrict any access.
Another favourite point of entry is roof lights, casement and sash windows, particularly the old wooden types with a few gaps they can breach, where they leave significant deposits of fluid and faecal residues with an offensive sickly smell.
Unfortunately if you have a problem with cluster flies it is likely you will most years, some seasons thy can be more prolific depending on their breeding cycle and climate conditions at that time.
As stopping the invasion is near impossible we are left with the task of dealing with them once they have breached our defences.
Signs that you have been invaded.
The first time you are aware of their presence may be if you have need to enter your attic to dig out those Christmas decorations or you employ a workman that needs access to the area. It can be quite a shock to discover the sheer number of flies that can be present.
You may also find they enter upstairs bedrooms it is amazing how they find a way in. you will suddenly notice a large number gathering in windows.
How to treat an attic area and products to use.
Fortunately there is quite a range of products available some are more successful than others depending on how you use them and where the problem is.
In the attic or roof space a smoke bomb is very effective at killing most of those present, leaving you with the task of hoovering up the remains. After this initial treatment a Prevent Cluster Fly Dispenser is a good way of mopping up those that remain or keep entering. This unit works by automatically dispensing a dose of natural pyrethrum based insecticide which it releases on a timed basis. The aerosol spray can last up to 60 days depending on the setting you use. More than one unit may be required depending on the area you are treating.
How to treat in a bedroom.
Bedrooms are a more tricky area as some people are affected by aerosol type sprays in a sleeping area. You could use a Prevent Cluster Fly Dispenser here if it is in a spare room and you can also turn it off when you feel it isn’t needed.
Cluster Buster window traps can be handy for more sensitive areas these powder traps fit onto the inside of the window glass at the bottom. The natural movement of the fly on glass causes them to fall into the trap. They then release a pheromone which attracts yet more flies. They can hold up to a 1000 flies and last two years.
How to treat living areas.
You can also use a good quality fly spray like Insecto or Bayer flying Insect spray. Close all windows stand in the centre of the room and spray for about 10 seconds in a circular pattern and then leave the room closing the door behind you.
Control or ignore?
Cluster flies have no recognized importance as carriers of disease, so are not a significant pathogenic risk. They should only be viewed as an unsightly nuisance and not as a sign of poor hygiene.
What is important to think about is that cluster flies will hibernate with other flies that ARE carriers of disease, such as blow flies found on faeces and rotting meat, the latter possibly attracted by the smell created by large cluster fly populations.