Sepsidae

Common Name

Black Scavenger Flies

Overview

Sepsidae, commonly known as black scavenger flies, are a family of small, thin flies with distinctive behavior and morphology. They are often associated with decaying matter and play a role in decomposition and nutrient cycling.

Taxonomy

Key Characteristics

  • Small size, typically 2-6 mm in length
  • Shiny black or dark in color
  • Distinctive wing-markings and often mimic ants
  • Long, slender legs
  • Males usually have enlarged forelegs used in mating displays

Life Cycle

  • Egg: Laid in decaying organic matter or dung
  • Larva: Maggot-like, feeding on decaying material or microorganisms
  • Pupa: Develops in the substrate where the larvae fed
  • Adult: Emerges to mate, often seen on flowers, dung, or decaying matter

Behavior and Ecology

  • Adults are often seen dancing or waving their legs, behaviors often linked to mating display and species recognition
  • Larvae play an important role in decomposing organic matter and recycling nutrients
  • Found worldwide in various habitats, particularly where decaying matter is present

Notable Species

  • Themira putris: Found in Europe and North America, often seen on decaying matter in moist habitats
  • Sepsis cynipsea: Common in the Northern Hemisphere, frequently seen on dung

Conservation

Most species in the Sepsidae family are not considered at risk. Their presence is generally a good indicator of the health of decomposing ecosystems.

Significance to Humans

Fun Facts

  • Some species engage in elaborate mating dances where males wave their forelegs and display wing markings.
  • Sepsidae flies often congregate on flowers, mistaken for pollinators, although they do not have a significant role in pollination.
  • The family gets its name from the Greek word "sepsis," meaning decay, which reflects their ecological role.
  • Male Sepsidae's enlarged forelegs are not just for show; they help in securing the female during mating.