Mating March Flies

Subject: Is this a type of fly?
Location: Lexington, MA
May 26, 2016 5:22 am
I live in Eastern Massachusetts and noticed these flying insects swarming all over our backyard. They don’t seem to bother humans but they really seem to like the grass seed on our overgrown grass. Can you please tell me what they are?
Signature: Gordon

March Flies
March Flies

Dear Gordon,
These are mating, sexually dimorphic March Flies in the family Bibionidae.  Males March Flies can be distinguished from females by their larger heads and bigger eyes.  We suspect because of your location they are most likely 
Bibio albipennis based on BugGuide information.

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