March Flies

Subject: what kind of insect is this?
Location: southeastern Pennsylvania
May 10, 2014 3:45 pm
I was playing with my son in the yard, when I felt something crawling on my leg. I let it walk onto my hand, and then I put it on the bush…didn’t want to squash them, while they were mating 🙂
We live in Southeast Pennsylvania, outside of Philadelphia. Photo was taken on May 09, 2014
Signature: Bob M.

March Flies
March Flies

Dear Bob,
These are March Flies in the family Bibionidae, and they are an example of extreme sexual dimorphism.  The male on the left has a large head and eyes, while the head and eyes on the female on the right are much smaller.  According to BugGuide:  “Adults emerge synchronously in huge numbers and often form dense mating aggregations. Males form loose “swarms” and copulate immediately with females as they emerge from the soil. After mating, female bibionines dig a small chamber in the soil with their fossorial fore tibiae, lay eggs, and die within the chamber (Plecia lay eggs on the soil surface). Adults are short-lived (3-7 days).”

Thank you for the quick reply. I appreciate the information, and your response.

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