Flies

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fly identification

Household flies, also known as true flies, are common nuisance pests often seen buzzing around and landing on surfaces. Unlike other indoor flying pests, flies only have a single pair of wings (alongside a pair of smaller club-shaped organs called halteres).

  • Flies have short lifespans, but they reproduce quickly in large numbers (a single female can lay up to 500 eggs).
  • Most species cannot bite, but there are exceptions such as biting midges and horseflies.
  • Flies have taste receptors on their feet, allowing them to assess the suitability of food sources before landing.
  • Due to their short and predictable life cycles, flies are often used in genetic research and forensic investigations.

Flies are drawn to the smell of food scraps, garbage, and any other type of fermenting or decomposing organic matter. They’re most commonly found in kitchens due to the abundance of food and moisture.

In addition to being a nuisance, flies can carry and transmit bacteria, viruses, and parasites on their bodies, contaminating food and surfaces that they land on. The common house fly is a potential vector of at least 65 diseases, including typhoid fever, dysentery, and cholera.

To prevent flies in your home, focus on eliminating their attractions: store food properly, clean up spills promptly, and dispose of garbage in sealed bins. Regularly clean kitchens and garbage areas, and address any potential breeding sites like leaky pipes or pet waste. Additionally, repair ripped screens and seal cracks around doors and windows to prevent entry.


House flies are the most common type of fly found indoors. They feed and breed on decaying organic matter, and are a common sight around kitchen garbage and spoiled food. Infestations are often a result of poor sanitation.

While they don’t bite, house flies have been known to transport harmful bacteria and can spread diseases like typhoid fever, dysentery, and cholera by contaminating food and surfaces.

Size: 1/4″ long (6 – 7 mm); about the size of a flax seed

Color: Dull gray and black with red eyes

Shape: Broad, oval-shaped body with large eyes, 6 legs, and 1 pair of wings

  • 6 legs
  • Tiny antennae
  • Large, red compound eyes
  • Broad, oval-shaped body
  • 4 dark, longitudinal stripes on the thorax
  • Striped or checkered markings on the abdomen
  • 1 pair of clear, membranous wings with a yellowish tinge at at their base

Fruit flies are attracted to ripened fruits and vegetables. They’re often brought into homes as microscopic eggs on the surface of moist or over-ripened produce from gardens or grocery stores.

Once inside, they mature and reproduce at an astonishing rate–a single female can lay up to 500 eggs, which hatch and become adults after about a week.

Fruit flies are generally harmless, but they may potentially carry bacteria and contaminate food.

Size: 1/10″ – 1/6″ long (3 – 4 mm); about the size of a sesame seed

Color: Brownish-yellow with red eyes

Shape: Slender, oval-shaped body with large eyes, 6 legs, and 1 pair of wings

  • 6 legs
  • Tiny antennae
  • Large compound eyes, usually bright red or reddish-brown
  • Slender, oval-shaped body
  • Black stripes on the abdomen
  • 1 pair of clear, membranous wings

Drain flies resemble tiny moths that infest bathrooms and kitchens in large numbers, usually as a result of a slow or clogged drain. They feed on bacteria and the moist, slimy, organic matter that collects around sinks, bathtubs, and floor drains.

They are weak fliers that tend to make short, hopping flights when disturbed.

Drain flies do not bite or spread diseases, but they can contaminate food and water. Heavy infestations may also trigger asthma and allergies.

Size: 1/8″ – 1/5″ long (2.5 – 5 mm); about the size of a peppercorn

Color: Light tan to dark grayish-brown

Shape: Fuzzy, moth-like body with hairy antennae, 6 legs, and 1 pair of wings

  • 6 legs
  • 13-segmented antennae with whorls of light-colored hairs
  • Fuzzy, moth-like body covered in a dense coat of fine hairs
  • 1 pair of broad, oval-shaped wings covered in grayish-brown hairs

Phorid flies are also known as “scuttle flies” because they are weak fliers and will instead try to escape danger by running and hopping erratically across surfaces.

They’re attracted to moist, decaying organic matter, which they feed and breed in. In addition to kitchens and bathrooms, they are also frequently spotted in basements, garbage containers, drain pipes, and wall voids.

Size: Varies by species, ranging from 1/64″ (0.5 mm) to 1/4″ (6 mm)

Color: Brown, black, or yellow

Shape: Hump-backed body with large eyes, 6 legs, and 1 pair of wings

  • 6 legs
  • Tiny antennae
  • Large, black compound eyes
  • Strongly arched thorax, giving it a hump-backed appearance
  • 1 pair of clear, membranous wings

Biting midges are tiny, bloodsucking flies that inflict sharp, painful bites on exposed skin, leaving behind burning or itching sensations, reddish bumps, and sometimes welts or blisters.

Due to their tiny size, they are hard to see and can easily crawl through window screens and door screens to get inside homes. They are most active around dawn and dusk, although biting can also take place at night.

Size: 1/25″ – 1/8″ long (1 – 3 mm); about the size of a chia seed

Color: Gray or black

Shape: Slender, oval-shaped body with a tiny head, 6 legs, and 1 pair of wings

  • 6 legs
  • 15-segmented antennae
  • Tiny head with large compound eyes and long mandibles
  • Slender, oval-shaped body
  • Long, tapered abdomen that becomes swollen and red after feeding on blood
  • 1 pair of membranous wings with light and dark markings

Dark-winged fungus gnats are small, short-lived insects that resemble tiny mosquitoes.

They normally live outside in moist soil where they feed on fungi and other organic matter. Indoors, dark-winged fungus gnats are typically spotted near houseplants, infesting potting soil.

Adult fungus gnats are completely harmless but their larvae are problematic, damaging roots and stunting plant growth.

Size: 1/16″ – 1/8″ long (1 – 3 mm); about the size of a chia seed

Color: Dark brown

Shape: Mosquito-like body with a long abdomen, segmented antennae, 6 spindly legs, and 1 pair of wings

  • 6 spindly legs
  • Long antennae with 8-16 segments
  • Small head with large compound eyes
  • Delicate, mosquito-like body with a long, slender abdomen
  • 1 pair of dark or smoky-gray wings