Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada

Species Megaselia scalaris

Megaselia scalaris - female Fly ID please - Megaselia scalaris small fly? - Megaselia scalaris - male compost fly - Megaselia scalaris Fast black flies that periodically infest Dr. Larry Marh's Drosophila lab at the University of California, Irvine - Megaselia scalaris - female Scuttle Fly with white tip - Megaselia scalaris - male Scuttle Fly with white tip - Megaselia scalaris - male Scuttle Fly with white tip - Megaselia scalaris - male
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Diptera (Flies)
No Taxon ("Aschiza")
Superfamily Platypezoidea
Family Phoridae (Scuttle Flies)
Subfamily Metopininae
Genus Megaselia
Species scalaris (Megaselia scalaris)
Other Common Names
Phoridae in general are known as Scuttle Flies, Humpbacked Flies, or Coffin Flies (see family page for origin of common names)
the most common species of phorid fly encountered in homes and other buildings; Phoridae specialist Brian Brown estimates that 90 percent of specimens sent to him for identification are Megaselia scalaris
body length of adult males 2+ mm; females 3+ mm
the female's abdominal tergite 6 is short, narrow, shiny, and extends laterally on the segment, unlike tergites of preceding segments [this feature can only be seen in a clear close-up photo taken at the proper angle, or by examination under a microscope]
cosmopolitan - Map (GBIF)
larvae live in a variety of habitats: moist decaying plant or animal material, sanitation filter beds, sludge in sewer pipes and trash cans in public washrooms and homes, lab cultures of Drosophila, fresh or fermenting fruit, and sometimes in external wounds or in the digestive tract of animals, including humans
larvae display a unique behavior of swallowing air when exposed to pools of liquid; the swallowed air allows them to float, and may prevent drowning during flood conditions in their normal habitat
year-round indoors
larvae are scavengers on a variety of decaying organic material
Life Cycle
see family page for description of the general phorid life cycle
page creation based on Brian Brown's identification of this image
See Also
"fruit flies" such as Drosophila are similar in body size (see comparison photos of D. melanogaster and Megaselia scalaris on page 4 of this PDF doc) but have a larger head and bright red eyes in life
Internet References
pinned adult images showing diagnostic characteristic on female abdomen (Brian Brown, Los Angeles County Museum of Natural History,
Questions and Answers on phorid flies (Brian Brown, Los Angeles County Museum of Natural History,
overview of habits and biology (Alan Christensen, U. of Nebraska)
account of myiasis [invasion of living tissue by dipteran larvae] by M. scalaris in wounds of hospital patient (P.R. Hira et al, Kuwait U., Kuwait, courtesy of US National Institutes of Health)
images of all life stages; PDF doc compared to Drosophila melanogaster, and discussion of adult & larva locomotion and behavior (D.A. Harrison and R.L. Cooper, U. of Kentucky)
Neotropical Entomology. First record of Megaselia scalaris (Loew) (Diptera: Phoridae) infesting laboratory colonies of Triatoma brasiliensis Neiva (Hemiptera: Reduviidae)