Mystery in the garden: Unknown Flies

Flies under row covers every year
April 20, 2010
When I lift my row covers, I have a zillion of these flies trapped underneath in early Spring. I’ve tried to identify them to no avail. Perhaps they originate in my compost.
North Central Arkansas


Dear Robin,
Flies are often tough for us to identify and we have to confess that we often make mistakes.  The behavior you describe seems like it points to Root Maggot Flies in the family Anthomyiidae.  It appears to us that the two flies in your photo might even be different species.  We will post you letter and images and request assistance from our readership.

Fly Head

Eric Eaton REsponds
Well, there are two different kinds of flies in the image.  The one on the left appears to be some kind of “march fly” in the family Bibionidae.  The other (on the right) is some kind of muscoid fly (“muscoids” is the term for flies that fall into several related families).  Without examining the actual specimen, I can’t tell what it is.

Thanks Eric for confirming our suspicions.

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