Fly Control in Toronto, Oakville & the GTA

• Common house fly

  Musca domestica

  Under 10 mm (3/8 inch) long, with four dark stripes down the thorax, the part just behind the head. It can't bite: its mouthparts sponge up food instead.

  Where found: Breeds outdoors in garbage, manure, lawn clippings, rotting fruit and vegetables and badly kept compost, then comes in through open doors and unscreened windows.

  Numbers peak in the hottest summer months. Almost every house fly indoors came in from outside, so the main fixes are sealing cracks, fitting screens and putting garbage out at least weekly.

• Cluster flies

  Pollenia spp.

  To most people they look like house flies, but they're a little larger, dull grey with golden hairs on the thorax, and slow. They gather at windows, often in rooms that aren't used much.

  Where found: Move into attics and wall voids in late summer and fall, then crawl out around window trim, baseboards and ceiling lights on warm days.

  They don't breed indoors, since their larvae live in earthworms, so the fix is an outside treatment in late summer.

  Cluster Fly Control →

• Filth flies (bluebottles, other blow flies and flesh flies)

  Calliphoridae, Sarcophagidae

  Blow flies are shiny metallic green or blue, 6 to 11 mm, and loud fliers drawn to lamps. Flesh flies are grey, 10 to 11 mm, with three black stripes on the thorax and a checkerboard abdomen.

  Where found: Dead animals, food waste and pet waste. A sudden swarm indoors in summer usually means an animal died in a wall or attic.

  House flies breed in garbage and manure too, and have their own card above. Flies from a dead animal can keep emerging for 1 to 3 weeks, then stop, because by then the carcass is too dry to breed in again.

• Drain flies (moth flies, sewer flies)

  Psychodidae

  Fuzzy, grey to black and moth-like, about 2 to 5 mm, with pointed wings often held like a roof over the body. They usually fly only a few feet at a time.

  Where found: Sinks, tubs and floor drains. The larvae live in the slime lining drains and traps, and in fridge and air conditioner drip pans.

  Bleach and drain cleaner do little to clear that slime, and boiling water alone doesn't reach the larvae. Scrub the pipes and traps with a stiff brush, then flush them with hot water.

• Phorid flies (humpbacked flies)

  Phoridae

  About 2 to 4 mm, tan to black, with a humped back and no red eyes. They run in jerky bursts across surfaces before flying off, which is why they're also called scuttle flies.

  Where found: Garbage, drain linings, broken disposals, wet potting soil and spilled food under appliances. Big ground-floor numbers can mean a broken drain or sewer line underneath.

  A few indoors is not unusual; large numbers usually point to a breeding source. A plumber can check the drain lines for cracks with a flexible scope or smoke.

• Fruit flies

  Drosophila spp.

  About 1.5 to 3 mm, usually with red eyes, a tan front and a dark rear. Small enough to get through window screens.

  Where found: Overripe fruit, rotting potatoes and onions, garden tomatoes and melons, drains, disposals, trash bins, unrinsed recycling and damp mops.

  They can go from egg to adult in about a week, and one forgotten rotting potato can breed thousands. Dark-eyed fruit flies breed more often in drains.

Drain flies, phorid flies, fruit flies and fungus gnats can breed and live entirely indoors. House flies and cluster flies come in from outside, and blow or flesh flies indoors usually point to a dead animal. Big, slow flies at sunny windows in fall and winter may be cluster flies: see cluster fly control. Tiny, slender flies around houseplants may be fungus gnats, which breed in overwatered potting soil. Bugs on sunny walls in the fall that aren't flies? See boxelder bugs and other fall invaders.