IDENTIFICATION GUIDE
Small flies: identify before treating
Five species under 3 mm look alike to the naked eye — and each breeds somewhere completely different. Getting the species wrong means treating the wrong place for weeks.
Active infestation? Don't wait — a certified technician responds within 4 hours, 24/7.
The rule that solves 90% of cases
Small flies are never the problem: they are the symptom. Each species develops in a specific organic material. Find that material, remove it, and the population collapses on its own — with no insecticide.
Vinegar fly (fruit fly)
DrosophilidaeIdentify
- Bright red eyes (sometimes black depending on species)
- Beige to light brown body, with dark bands on the abdomen
- Characteristic notch on the wing margin
- Slow flight, lands frequently
Where it breeds
Fermenting fruit and vegetables, bottle and can dregs, damp organic matter, bar drains, under equipment, poorly rinsed recycling bins.
What solves it
Eliminate the fermenting source, sanitize thoroughly, then trap to measure the result. Spraying without removing the source only buys a few hours.
Humpbacked fly (phorid)
PhoridaeIdentify
- Humped outline: markedly arched thorax, small low-set head
- Enlarged hind femur
- Wing without cross-veins
- Runs erratically on surfaces rather than flying off
Where it breeds
Damp decomposing organic matter. In a building the source is very often underground: a cracked drain, a broken sewer line under the slab, a dry trap. Persistent presence warrants a plumbing inspection.
What solves it
Sanitation and repair of the source. This is the species whose repeated presence should raise suspicion of a structural break rather than a mere cleanliness issue.
Fungus gnat
SciaridaeIdentify
- Dark, slender, elongated body, like a tiny mosquito
- Long antennae
- Clearly visible Y-shaped vein on the wing
- Weak, hesitant flight, near the floor or plants
Where it breeds
Fungi developing in potting soil, decomposing vegetation, rotting roots, damp wood. In businesses, often decorative plants or overwatering.
What solves it
Let the potting soil dry several centimetres between waterings and trap the adults. No insecticide is needed once the moisture is corrected.
Drain fly (moth fly)
PsychodidaeIdentify
- Dark, stout, hairy body, like a small moth
- Wings folded roof-like over the body at rest
- Parallel, hair-covered wing veins
- Long antennae; flies in short clumsy hops
Where it breeds
Organic sludge film lining the inside of drains, traps, septic tanks and under toilets. Larvae live in this biofilm, out of reach of any sprayed product.
What solves it
Mechanical removal of the biofilm (drain brush) plus enzymatic treatment, with plumbing correction if needed. Pouring boiling water or bleach does not destroy the biofilm at depth.
Small dung fly
SphaeroceridaeIdentify
- Dark body bristling with thick setae
- First segment of the hind tarsi distinctly widened and shortened
- Very small, often mistaken for a vinegar fly
Where it breeds
Advanced decomposing organic matter: sewage, manure, drain sludge, garbage, animal matter. In urban settings, often linked to a sewer backup or a poorly maintained waste room.
What solves it
Locate and remove the decomposing matter, then sanitize. As with the phorid, a persistent population points to a structural sanitation problem.
Frequently asked questions
Why do the flies come back after spraying?+
Because the insecticide kills the flying adults, not the larvae developing in the source — drain biofilm, fermenting fruit, damp potting soil. A new generation emerges within days. As long as the organic matter feeding them remains, the cycle restarts indefinitely.
How do I find which drain the flies come from?+
The tape test: place clear tape, sticky side down, over the drain opening overnight without fully sealing it. In the morning, emerging adults are caught on it. Repeating this on each drain isolates the source precisely.
Is it a cleanliness problem?+
Not always. Vinegar flies and drain flies are often maintenance-related, but the phorid frequently signals a structural break: a cracked sewer line under the slab, a dry trap, an invisible leak. A spotless facility can have a phorid problem.
How long does it take to eliminate small flies?+
Once the source is removed, adults generally disappear within 1 to 2 weeks, the time for the last generation to die off. If the source is a plumbing break, the timeline depends on the repair — no treatment substitutes for it.
Flies that keep coming back?
We identify the species, trace the source — often a drain or a leak — and document the intervention. Free inspection.