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Manitoba Museum

Flies (Diptera)

Parasitic Flies


The Parasitic Flies are a large family with over 700 species in Canada. Their larvae are internal parasites of other insects. The preferred hosts of these species include butterflies and moths, beetles, and the grasshoppers, crickets, and katydids. Some species are very good at mimicking the colouration and behaviour of wasps. Adults feed on liquids such as plant nectar and insect honeydew.

Representative Genera and Species:

Archytas, Cylindromyia interrupta, Gonia, Lydina, Lypha, Mochlosoma, Tachina

Pollinator Life Cycle:

Some males “hilltop” at mating time by flying to upland areas and waiting there for females. Adaptations of the female reproductive system facilitate a variety of egg-laying strategies. Some for example, inject eggs into the host’s body cavity using a specialized piercing organ. Larvae develop inside the host and are able to avoid defence mechanisms. Pupation then occurs in a puparium inside the host body, or in soil or ground litter. Some species overwinter in this stage.

Rarity Status:

No Parasitic Flies are legally protected in Canada. The status of Canadian species has not yet been assessed.

Physical Appearance:

Adults are small to large (2-20 mm), with heavy bristles on their abdomen. They exhibit variation in shape (slender to robust) and colour (yellow, black, metallic blue/purple/multicoloured). Mimics have a wasp-like abdomen and striped thorax. These flies have sucking mouthparts, two membrane-like wings (darkened/patterned in some species), and tiny to enlarged antennae. They are characterized by their well-developed postscutellum.

Pollinator Habitat:

These flies are very diverse and may be found in almost every terrestrial habitat. Adults are commonly located on wildflowers, in meadows, and along railways.

Canadian Distribution:

  • Alberta
  • British Columbia
  • Manitoba
  • New Brunswick
  • Newfoundland/Labrador
  • Northwest Territories
  • Nova Scotia
  • Nunavut
  • Ontario
  • Prince Edward Island
  • Quebec
  • Saskatchewan
  • Yukon

Prairie Types:

  • Fescue Prairie
  • Mixed Grass Prairie
  • Tall Grass Prairie
Parasitic Flies