Ask The Entomologist Question About Stable Flies

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Hi there, I have recently and for the first time in my life, had house flies land on me and do “something” that hurts. It doesn’t look like they are biting but doing something with their regurgitating/sucking bit. They are definitely house flies (not horse flies, deer flies etc) and it seems very strange that they have started doing this…..it hurts! By the way, I’m from Canada, but I thought you could help. Thanks.


What you are probably experiencing are stable flies.  Stable flies resemble house flies but they bite.  In fact, sometimes they are referred to as “biting house flies”.  The adults feed on blood from almost any warm-blooded animal.  The larvae feed and develop in decaying animal and plant wastes.  They prefer excrement mixed with straw, soil, or grain but can also be found in wet straw, hay, grass clippings, and poorly managed compost piles.  They typically remain active through October but once the temperatures fall below freezing they will die off.