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How Do Cluster Flies Survive in the Winter?

It’s bad enough having flies buzzing around and being generally annoying in the summer months, but dealing with them during winter is intolerable. By learning why they are around during these chilly days, will help you know what preventative measures you need to take to keep them out of your property. 

an upclose shot of a cluster fly

Cluster Flies During Cold Winter Months

During winter, out of the fly species, it’s cluster flies that will cause you the most problems when indoors. This is due to them being a wintering pest, meaning they actively seek shelter to escape from the cold weather to lay their eggs. In fact, this is why they are more commonly seen during this time of year. Eggs which were laid at the end of autumn are now beginning to hatch, and the flies continue to rapidly reproduce, creating a cluster of problems for you. 

Though cluster flies are a nuisance, luckily, they don’t pose any health threats to humans by biting or spreading diseases. They are more problematic because of the size of the infestation that they can create.

How to Tell the Difference Between a House Fly and a Cluster Fly

Both cluster flies and house flies look alike, however, there are some ways to tell them apart. 

Cluster flies:

  • Are slightly larger than house flies
  • Have chequered patterns along their abdomens. With a spot or stripe located behind their head and yellow hairs on their lower bodies. 
  • Have wings that overlap when they are resting
  • Move more slowly
  • Gather in large groups

Where Will I Find Cluster Flies Indoors?

Typically, cluster flies look for warm and secluded places to huddle together and enter diapause (a period of suspended development). This makes the flies hard to find and control over the winter months.  

This includes areas such as:

  • Loft spaces or basements 
  • Within walls and crevices
  • Garages
  • Around windows and behind curtains 
  • Behind picture frames
  • Underneath furniture 

On warmer days, you may see cluster flies re-emerge in order to regain heat and energy. 

Should I Wait for Cluster Flies to Go Away on Their Own or Take Action to Remove Them?

Around Spring time, cluster flies typically will leave your property back into the outdoor warmth. However, not many people would want to wait until then if they have discovered a cluster fly infestation in their homes. Depending on the infestation, if the problem is not dealt with for a long period of time, you may end up with a larger, out-of-control, infestation on your hands. 

Due to the flies hiding inside the walls of a property, by entering through cracks and crevices, it makes getting rid of them a problem. If you try and seal up these entry points, you will trap the flies inside where they will die. However, this may attract even more unpleasant pests along the way. 

So, what can you do? You have a few options, including: 

  • Vacuuming up visible flies
  • Using flypaper or sticky traps
  • Applying a safe and approved indoor pesticide

Once the flies have left your property, it is then advised to seal up any gaps around windows, doors, vents, electrical outlets, or walls. Along with fixing any insect window screens. This will prevent re-entry later down the line.  

Need Help from a Pest Control Expert?

If you are concerned that you have a problem with cluster flies, then we’re here to help. Please get in touch, and we will be happy to carry out a free of charge inspection and advise on the best course of action.

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