cluster flies

Tips for Preventing and Treating Cluster Flies

In late Fall and early Winter many homeowners notice large flies gathering in warm windows, in attics and loft spaces. These flies are called Cluster Flies. During Winter, Cluster Flies hibernate indoors where it is warm. You will often find them “clustered” in groups on the warm sides of your home. Jackie Davis from Cottage Life states, “Cluster flies don’t feed, breed, or lay eggs inside, so if you do nothing, they’ll either leave on their own, or die”. Really, they are just a nuisance, with their loud buzzing and the feeling of unease created by having creepy crawlies on your ceiling. Here are a couple ways to keep your home Cluster Fly free this Winter.

Close all cracks and crevices on your home

The first and best defense against Cluster Flies is to keep them from coming into your home. Cluster Flies are attracted to the warmth of a heated space and usually enter homes through small cracks and crevices. Make sure to seal up all these areas around your home including windows, doors, siding, utility pipes, behind chimneys and under fascia with good quality caulking. Make sure to do this well before cool temperatures arrive.

Patch or replace all window and door screens

Torn window and door screens are a easy way for Cluster Flies to enter your home. Patch or replace these before cool temperatures arrive.

Use a fly swatter or vacuum

If Cluster Flies do get into your home, and on warmer days find their way out of hibernation you will notice their sluggish buzzing around your house.  If they become bothersome, the simple use of a fly swatter can remedy the problem.

A vacuum is also an option if they are clustering in accessible windows or ceilings.

Do not use insecticides

FightBugs.com states that timing of insecticide sprays for Cluster Flies is crucial. Too early and the insecticide gets broken down by the sun and does not effect the flies, too late and the flies are already in your house. In addition, insecticides must be sprayed every year. We do not recommend spraying insecticides on the interior or exterior of your house.  The danger to you and your family far outweighs the benefits. We also do not recommend using an insecticide powder to kill flies where they cluster, this will cause the flies to die in your walls which could then attract Carpet Beetles. Carpet Beetles then feed on the dead flies and can wreak havoc on woolens, dry goods and other natural items in your home.

Practicing preventative tactics is really the best way to deal with Cluster Flies, if they can’t get in, they can’t bother you.  It may take several years of regularly sealing cracks to eliminate Cluster Flies, but in the end your work will pay off.

Reference sites:

http://ento.psu.edu/extension/factsheets/cluster-flies

http://www.orkin.com/flies/cluster-flies/

http://cottagelife.com/environment/how-to-get-rid-of-cluster-flies

http://www.fightbugs.com/get-rid-cluster-flies/

One thought on “Tips for Preventing and Treating Cluster Flies”

  1. Best insecticide to get rid of flies is the one which has an pheromone included and attracts the flying insects from distance. It’s not needed to treat all the surface, just 10 – 15%.

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