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Dung Scavenger Fly - Sepsis punctum

Truth be told, this individual on showcase could be any North American Sepsis Fly specie, but I’ve chosen to settle on the specie that it’s most likely to be. Most species of Sepsis from what I’ve seen share similar characteristics: small, compact, somewhat shimmering body, 1 spot near their wing’s edge, and pronounced compound eyes on the side of the head, rather than all encompassing compound eye like most other Flies have. This does make this family of Flies quite distinct however in terms of morphology, even if they share other behaviors with fellow Flies. These Flies belong to the family: Sepsidae - Ensign or Scavenger Flies; most Flies can scavenge, so this blog will know them as Ensign Flies. Have a close look at these images... you know they’re Flies, but don’t they resemble something else? Look at their thorax-abdomen area for a clue. Hmmmm...

Sepsis Flies are actually effective mimics of Ants! It continues to astound how well Flies can use mimicry to their advantage by copying Hymenopterans! Their body shape mimics the narrow waist that Ants have, and it’s not uncommon for Ants to be seen with wings, especially in groups (there were several individuals near this one, but flew away when I approached the hosta plant). Even their lustrous body can give more credence as Ants can be glossy in appearance. Mimicking Ants is very useful as they tend to be ignored as prey items given their tendency to swarm and bite. This allows most of the Flies to go about their day in peace, which in this case is looking for sources of dung to lay eggs on or for flowers to enjoy a nectar meal. I’m not certain if this goes for this specie in particular, but it seems other species of Sepsis Flies don’t actually emerge from dung or decaying food sources until they’re full-fledged adults. They may not look it, but these Flies are taking decomposing very seriously.

Pictures were taken on May 26, 2019 with a Samsung Galaxy S4