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Manitoba Museum

Flies (Diptera)

March Flies


Also called Lovebugs, these flies are abundant in spring and early summer. Larvae feed on plant litter, decaying organic matter, and underground plant structures. Some are considered crop pests. Adults feed mainly on nectar and pollen, honeydew, and other plant liquids, though some rely solely on food consumed during the larval stage. They are pollinators of wildflowers, shrubs, and small trees. They can be important pollinators in orchards, and to some species of orchid and iris.

Representative Genera and Species:

Plecia heteroptera

Pollinator Life Cycle:

Adults emerge simultaneously, often forming large swarms. Males mate with females immediately upon emergence, staying attached to them for several hours to days. They employ special strategies to ensure that their sperm stays in place when females mate with other males. Some females then lay eggs in a chamber in the soil, dying shortly after. Others may lay them on the soil surface. Adults generally live a short time, about 3-7 days.

Rarity Status:

The status of Canadian species has not yet been assessed, and none are legally protected.

Physical Appearance:

These small to medium flies are 5-12 mm long with robust, hairy bodies. They are usually black, often with a brightly coloured thorax (red or yellow). Wings are clear or dark, with distinguishing venation. Males have characteristically large eyes, divided into upper and lower sections. The short, six or more segmented antennae sit low on their face.

Pollinator Habitat:

Larvae live in soil, leaf litter, rotten wood, feces, decaying organic materials and among roots of grasses and plants. They occur in grassy meadows, forests, and pastures. Adults are frequently found on flowers.

Canadian Distribution:

  • Alberta
  • British Columbia
  • Manitoba
  • New Brunswick
  • Newfoundland/Labrador
  • Nova Scotia
  • Ontario
  • Quebec
  • Saskatchewan
  • Yukon

Prairie Types:

  • Fescue Prairie
  • Mixed Grass Prairie
  • Tall Grass Prairie
March Flies