• Genus: Clogmia
• Species: Clogmia albipunctata
• Synonym (older name): Telmatoscopus albipunctatus (“white-dotted”)
• Common names: “drain fly and filter fly”
• Common name “Moth fly” applies to several Genera in Psychodidae, but in structural pest control, albipunctata is generally the most common species. The older synonym T. albipunctatus may appear in literature and on some identification keys.

Identification:

• 13 to 16-segmented antennae, often with whorled setae
• Wings with reduced venation and lacking distinct cross-veins
• Wings held roof-like at rest; heart- or leaf-shaped outline

MFs are small, dark gray to brown flies (2 to 5 mm) with a characteristic moth-like, fuzzy appearance, Adults prefer to hop or make short fluttering flights.

Habitat & behavior:

• MF is endophilic (indoor environment preference).
• Species are synanthropic (live near humans and benefits from human activity) and may be found indoors year-round in and around temperature-controlled environments.
• Adults are most active at dusk and night (crepuscular, nocturnal).
• Poor fliers and typically remain within meters of resource or larval sites.
• Inspect for resting adults on nearby walls, tiles, or light-colored surfaces within 1 to 2 meters of the suspected drain or other resource sites.
• Adults resting on a wall(s) often pinpoint the exact drain or wet niche (larvae refugia).
• Tolerate low-oxygen, contaminated environments.
• Resource sites include wet, gelatinous biofilms composed of fermenting organic material, black water, and effluence.
• Develops within filters, drains, sump and elevator pits, septic tanks, sewer breaches, and sewage treatment plants.

Public health significance:

Estimated time sequence for fly surface behavior.

Primarily a nuisance, MFs can transfer opportunistic pathogens from drains, and other contaminated sites, to nearby surfaces. Indoor sudden emergences are biological indicators of drainage, waste, and vent (DWV) failures, dry drain traps, or cryptic moisture reservoirs that require corrective action.

Lifecycle (Holometabolous or “whole change”)

• Reproduction: Oviparous (place eggs in/on wet organic bio-films)
  Development: Egg (resource sites), larva-four instars (moist), pupa, adult (free, short ranging)
• Egg to adult in 14 to 30 days depending upon environmental conditions and substrate quality
• Development slows significantly below 16°C (60°F) and may stop below 10°C (50°F)
• Larvae are aquatic/semi-aquatic, feeding upon bacteria, algae, and organic detritus within film layers
• Pupation often occurs just above the waterline or on damp surfaces near the larval site
• Adult lifespan 1 to 3 weeks
• Indoor en masse sudden emergences of adult flies are a primary biological indicator of a sewer system of septic system malfunction or failure

Quick facts:

Environmental role:

MFs accelerate the decomposition of organic matter by grazing on microbial bio-films and play a role in nutrient recycling. In and around structures, MFs indicate moisture intrusion and biofilm accumulations.