April 19th, 2022 by Sarah Miles

And why timing is of the essence

It goes without saying that nobody relishes the idea of any kind of pest infestation in their homes. Cluster flies are not only unpleasant, living in large numbers (hence the name) in your home, but if you don’t deal with them before they leave in the spring, it won’t be a final ‘au Revoir, more a temporary ‘à bientôt’. To paraphrase Arnie, they’ll be back.

What are cluster flies and how are they different to regular house flies?

Cluster flies have several distinct differences from house flies. They are slightly bigger (around 8mm long) and appear more golden yellow than black due to the gold hair on their thorax. While they live en masse, don’t assume that they’re not Cluster Flies you’re seeing because there are only a few; they like dark, quiet areas so they are most commonly found in lofts or garages. Be vigilant for stains on the walls and/or a sickly, sweet aroma. This is a sign that you have them.

Why timing matters

The sickly smell and stains are due to them rubbing their saliva into the walls. This isn’t just an act of fly vandalism; it has a specific purpose: to guide them back in the autumn. Cluster flies will leave your home in the spring when they go out to mate during the warmer months. You may think, therefore, that there’s no urgent need to eradicate them as they’ll just leave of their own accord.

However, that’s not the full story. When the weather becomes colder again later in the year, they will seek refuge and the scent guides them back to their previous location. That’s because the saliva contains pheromones which act as a marker, bringing them right back again.

Break the cycle

It’s impossible to remove all traces of the pheromone once they’re gone so simply scrubbing the walls won’t work. You need to eradicate them before they leave in the spring. That’s because the pheromones are specific to the flies in your infestation. Therefore, kill the flies and you break the cycle.

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But how do you kill them?

The cluster flies’ greatest defence is their number. There are just so many of them that they are likely to overwhelm individual fly killing treatments. If you miss any, they’ll just come back and reproduce, and you will be back to square one.

The best strategy to remove them all is to use a combination of treatments to cover all bases. The most effective treatments will be smoke bombs, dusting powder, and automatic aerosol dispensers.

Smoke bombs can be really effective due to the way they get into every corner of the space. This will also help to flush them out.

Being dry, the dusting powder can be used in areas where a spray cannot, such as around sockets, and switches. It’s also good for getting into corners and cracks. Anything that comes into contact with it will be killed.

Cluster Fly Aerosol and Dispenser Pack

This Automatic Dispenser is suitable to house the PreVent Auto Aerosol to tackle cluster flies in spaces difficult to reach such as your loft or attic area.

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If you don’t fancy standing in amongst them to spray them with insecticide as they’re flushed out by other measures, an automatic aerosol is ideal. This will release spray automatically in programmable intervals, so you can leave them to work while you stay well away.

An important contributor to the success of your eradication strategy is to repeat these treatments several times to make sure you have killed all of them. While you may think that seems like a lot of effort now, it’s so much better than a reinfestation in a few months because you didn’t do the job thoroughly enough.