The Flesh Fly

Common Name:
Flesh Flies
Scientific Name:


The common name of flesh fly comes from the fact that the larvae of most species develop in spoiling meat and decayed flesh. Some species are beneficial because they are parasitic on arthropod pests. Because they develop in fecal material or garbage, some species are of human health concern. Some species can cause subcutaneous or intestinal myiasis in humans. There are about 327 species of flesh flies in the United States and Canada.


Adults usually about 1/4-7/16" (6-11 mm; range 2.5-18 mm) long; relatively large, robust flies. Color dull blackish gray; eyes often reddish; thorax usually with 3 black longitudinal stripes; abdomen often with checkerboard pattern of black and gray spots, but sometimes striped, banded, or spotted, whose markings usually shift from dark to pale depending on the viewing angle, and tip of abdomen usually red or pink. Mouthparts sponging. Antenna with arista plumose/feathery only in basal 2/3's to sometimes bare. Thorax usually with postscutum (area below scutum) not developed; usually with 4 notopleural bristles; hindmost posthumeral bristle located even with or toward midline from presutural bristle; hypopleuron (plate just above middle coxa) with bristles. Wing with 4th (3rd long) vein (M) strongly angled forward, cell R5 narrowed but rarely closed distally (at wing margin). Mature larva about 3/8-3/4" (9.5-20 mm) long; eyeless, legless, and tapered towards head from large rounded rear segment, head represented by 1 pair of dark hooks, Color white or pale yellowish.

Posterior spiracles (breathing pores) sunken within oval cavity surrounded by usually 12 tubercles (range 8-12), 2 plates each with 3 spiracular openings/slits (lst and 2nd instars with only 2 slits), slits straight, inner slit directed away from midline ventrally, each plate surrounded by an incompletelonce-broken dark ridge (peritreme); button (round ecdysial/molting scar) absent; trachael tubes leading from spiraclar plates at most barely visible; spines on anal protuberance (below spiracular plate cavity) not arranged in a "V" pattern.


  1. House (Musca domestics) and Face (M. autumnalis) flies have thorax with 4 dark longitudinal stripes, abdomen lacking black and gray checkered pattern.

  2. Little house (Fannia canicularis) and Latrine (F. scalaris) flies have wing with 4th (3rd long) vein straight.

  3. Stable (Stomoxys calcitrans) and False Stable (Muscina stabulans) flies have wing with 4th (3rd long) vein curved towards 3rd vein but not sharply angled; in addition stable flies have piercing mouthparts and thorax with pale spot behind head while false stable flies have sponging mouthparts but a pale scutellum (rear tip of thorax).

  4. Cluster fly (Polienia rudis) has thorax without stripes but covered with golden hairs.

  5. Blow flies and Bottle flies (Calliphoridae) are partly or wholly metallic blue, green, or dull brassy, or sometimes dull black, thorax lacking stripes and tip of abdomen not red/pink.


  1. Sarcophaga bultata Parker. Adults about 5/16-5/8" (7.5-15 mm) long; color gray, thorax dorsum with 3 black stripes, abdomen with a slender median black stripe and checkered with shifting pattern; antennae arista long-plumose; mesothorax dorsum with 1 st longitudinal row of bristles to each side of midline (postsutural arcostichal setae) with bristles just before scutum well developed; middle tibia without but hind tibia with fringe of long hairs to inside; found throughout the United States and in southern Canada from Brisith Columbia to Quebec.

  2. Sareophaga haemorrhoidatis (Fallen). Adults about 3/8-9/16" (1 0-1 4 mm) long; thorax dorsum with 3 black stripes, abdomen checkered with shifting pattern; antennal arista long- plumose; head with rows of frontal bristles (on face to either side of swollen median vertical area and antenna] bases) diverging below; mosothorax dorsum with Ist longitudinal row of bristles (postsutural arcostichal setae) with bristles just before scutum absent or at most rudimentary; hind tibia lacking row of long hairs to inside; found worldwide.

  3. Wohifahttia vigil (Walker). Adults about 3/8-5/8" (10-15 mm) long; head with palpi yellow, thorax dorsum with 3 black stripes almost fused together, abdomen black with 4 longitudinal rows of small gray spots, 2 down middle of segments and 1 on each side, pattern not shifting with change of viewing angle; antennae arista appearing bare but with very short hairs; parafacial (head area between lower 1/3 of eye and vertical front ridge (goes around antennae bases)) bare, without hairs/selae; hypopleuron (scierite/piece just above middle coxa) with both bristles and short hairs; found primarily in northern United States including Alaska, and Canada.


Females are larviparous or give birth to larvae/maggots instead of laying eggs. Larvae are laid on the larval food material. Many species develop in excrement or decaying flesh, some are parasitic, and others can develop in a variety of materials. Pupation usually takes place in the top 2" (51 mm) of soil. The life cycle (adult to adult) varies with the species, with a range of 8-36 days.

Biological notes and developmental/life cycle times can be summarized for some of the more common flesh flies as follows:

  1. Sarcophaga bullata. Average rearing data at 72'F/22'C and 50% RH is as follows with the range in parenthesis: Ist instar 26 hrs (24-36), 2nd instar 18 hrs (14-24), 3rd instar 54 hrs (30-72), prepupa 112 hrs (54-192), pupa 12 days (11-17), total for immatures 17 days (16-20). Larvae of this species commonly occur in animal wounds. They have caused dermal myiasis in humans. Adults have had polio virus and Theiler's mouse encephalomyelitis virus associated with them.

  2. Sarcophaga haemorrhoidalis. Average rearing data at 77'F/25'C is as follows with the range in parenthesis: lst instar I day (1), 2nd instar 1 day (1-2), 3rd instar 2.2 days (2-4), pupa 11.5 days (11-13), total for immatures 15.7 days (15-20). The larvae can cause wound myiasis in humans resulting in deep and serious lesions. Within Sarcophaga, this species is responsible for the authentic cases of human gastrointestinal infestation. Such infestation has lasted for up to 6 years and introduction is usually by consumption of contaminated meat or other food. Adults are associated with dozens of disease organisms including polio virus, E coli (Migula), salmonella, Shigella dysenteriae (Shiga), Streptococcus spp., tapeworms, etc.

  3. Wohlfahrtia vigil. In southeastern Canada, the life cycle (adult to adult) requires 30- 36 days as follows: larviposition occurs 11 -1 7 days after adult emergence, larvae mature in 7-9 days, emerge, drop to the soil to pupate, and the pupal period lasts 10-12 days. Human cases of myiasis involve infants under 5 months old. The larva penetrates the skin directly and produces a small boil-like swelling with a circular opening, each about 1/4-3/4" (6-20 mm) in diameter; typical number of lesions is 12-14 but as high as 40. They cause the same problem on other young mammals such as mink, dogs, cats, rodents, rabbits, and foxes.

  4. Blaesoxipha spp. Members of this genus are beneficial insects because the larvae are parasitic on grasshoppers, and are commonly called grasshopper maggots. They are found throughout the United States.

  5. Sarcophaga aldrichi Parker. Larvae of this species are important parasites of the pupae of the forest tent caterpillar, a common pest of sugar maple trees. Although beneficial, their numbers can make them a nuisance pest in southern Canada and much of the eastern and Midwestern United States.

  6. Eumacronychia spp. Most of these live in wasp nests where they kill the wasp egg/larva and feed on the provisioned food.


Adults are typically found outside on flowers or on larval food materials such as excrement, decaying flesh/carrion, decaying vegetable matter, garbage, and animals which they parasitize such as insects, snails, and other invertebrates, turtles, humans and other mammals, etc. Dead rodents, birds, and other small animals can be the source of flies within structures while dog excrement and garbage are the common outdoor sources.

They are mostly attracted to carrion or excrement exposed in sunlight and usually arrive after the blow flies. Adults show greatest activity at temperatures of 76-82'F/24- 28'C and prefer 54-56% RH. Outside, they prefer stone walls as resting sites.

Mature larvae usually leave the breeding source in search of a drier place in which to pupate. Hence, occasionally mature larvae/maggots can be found crawling about inside a structure.