Schedule Service
moth flies


Moth flies are approximately 1/8 of an inch in length with its entire body and wings covered in tiny hairs, giving them a moth-like appearance. Most species are black in color but at least one commonly encountered species is mousy brown. Antennae are 13-segmented with each segment having a bulbous swelling and circle of long hairs. Moth flies are weak flyers and can be carried on the wind from their breeding sites to structures. Eggs are usually laid in gelatinous material lining drains and other basins, hatching in 32 to 40 hours. The larvae and pupae live in the gelatinous film with breathing tubes projecting through the film. They are difficult to drown and, in some cases, can survive submersion up to two days. Moth fly larvae feed on sediment, decaying vegetation, and microscopic plants and animals and pupate in 9 to 15 days. The brief pupal stage lasts from 20 to 40 hours. The entire life cycle can be completed in 8 to 24 days, depending on environmental conditions.

Biology and Behavior

moth fly

  • Common problem areas include nearby sewage facilities, storm drains, leaking septic tanks, elevator pits, sump pits, floor drains, bath traps and voids under showers, bathtubs and mop sinks.

  • Commercial kitchens that 'wet wash' with pressurized water often push moist organic debris into cracks under equipment and gaps under walls where the material ferments and breeds moth flies.

  • The most difficult infestations are caused by sub-slab breaks in drain lines where organic material accumulates and adult flies or larvae enter the living space through cracks in the slab, gaps around utility penetrations or unsealed expansion joints.

  • Such sub-slab infestations can only be found by boroscopes used to locate broken lines or by cutting a core hole in the slab to look for conducive conditions or signs of activity. All infested soil must be replaced and the leak repaired to solve these problems.

  • Wet mops and brooms that collect moist organic material and are not cleaned and improperly stored are also good breeding sites.

Moth Fly Prevention Tips

  • Insect light traps are effective against adult moth flies but will not solve a problem on their own as developing flies will remain.

  • Hot water, bleach and caustic cleaner applications to drains without removing the slime layer first are ineffective treatments.
  • Eliminating the breeding sites through sanitation and moisture control are the only methods for long-standing control.

  • Applications of bioenzyme-based cleaning agents and growth regulators are beneficial in eliminating organic material in unseen microenvironments.

  • Cover gaps leading to suspected, hidden breeding sites with tape to trap emerging flies and show activity.

  • Do not stop searching when one source of infestation is found. There are often more.

Action's Moth Fly Control Services


Schedule Your Free Inspection

Complete the form below to schedule your no obligation inspection.

For Expedited Service Call (877) 420-0849