SPECIES ID / Invertebrates

True Flies

Rat-Tailed Maggots

  • 165 aquatic or semi-aquatic species in North America
  • Many more terrestrial species
  • Also known as Flower Flies
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Syrphidae

Identification Tips:

• Body length 4-16 mm without breathing tube; up to to 70 mm with it
• Body cylindrical and thick with rounded front
• Head not visible; encased in body
• Variable number of pair of short prolegs on body
• Long telescopic breathing tube extends from rear of abdomen; may be several times body length when fully extended

Life History:

• Found in calm shallow water at margins of ponds, wetlands, and stream pools
• Usually found burrowing in decaying organic matter
• Can live in water with no oxygen; breathe air via a tube extending to the surface

• Usually found in or around flowers
• Often hover motionless in air

Very Sensitive Somewhat Sensitive Facultative Somewhat Tolerant Very Tolerant
Pollution Indicator High abundance indicates severe organic pollution

Primary Information Source:
Voshell, J. Reese. 2002. A Guide to Common Freshwater Invertebrates of North America. McDonald and Woodward Publishing Company. Blacksburg, Virginia.