Phorid or humpbacked fly, family Phoridae
Tom Myers

Small flies are a common problem in restaurants, bars and other food-service accounts, particularly in those instances where sanitation is poor. To successfully address small fly problems in commercial accounts, knowledgeable PMPs suggest an IPM approach featuring: inspection, sanitation, exclusion, monitoring and treatment.

Inspections should focus on problem areas to ensure that good sanitation practices are being used to eliminate small fly breeding sites. Drains, cracks and crevices, and areas that collect organic matter should be treated with microbial products that can eliminate the breeding sites, they advise.

Replacing traditional cleaning products with microbial cleaners is key in preventing new infestations while helping to eliminate current populations.

Small flies become a problem when they are breeding inside accounts, typically in scum and organic filth. Because these flies all have a very short life cycle, just killing the adults with sprays or fogging won’t help for long. Biosanitation products based on friendly organic waste-eating microbes are an ideal choice for sanitation in areas with chronic moisture problems. These products are applied and not rinsed off, and the microbes go to work eliminating odors and digesting the organic buildup. In addition, insect growth regulators (IGRs) are effective at breaking the life cycle of the flies. They can be blended with biosanitation products or applied separately.

Common fruit fly (Drosophila melanogaster)

TOUGH OPPONENT. PMPs know that pesticide baits and residuals work well in controlling ants and cockroaches, says Tom Dobrinska, Anderson Pest Solutions, Elmhurst, Ill., “but there’s no real ‘magic bullet’ that will completely wipe out a small fly infestation,” he cautions.

“Look at the reproductive potential of small fly species. For example, a red-eyed fruit fly female can lay up to 500 eggs in a short life span. Do the math,” he suggests: “In three weeks that will produce 125,000 adult fruit flies under ideal conditions. If you achieve a 99 percent reduction in that population, that still leaves 1,000+ fruit flies. So it’s paramount to eliminate every source they can possibly breed in. Improving sanitation and odor control, along with eliminating larval harborage material, will help bring about a successful control program.

“Effective sanitation procedures that zero-in on food preparation, food manufacturing or food-processing areas will help reduce the breeding and feeding of the various small fly species. And utilizing biological products that eliminate odor and eat organic residues also are helpful. If these pests cannot detect a source by smell, they’ll head somewhere else.”

Dobrinska maintains that correctly identifying the invading small fly species is critical for control, because if you know their habits and biology, that will just about guarantee a successful inspection of the infested area.

“Because food and beverage facilities clean with lots of water, you need to inspect areas under equipment and inaccessible drains,” he says. “Once the source is identified, the pest technician and the facility manager can develop a fly control strategy for that situation.”

Close up of common fruit fly (Drosophila melanogaster)

Small fly control professionals advocate procedures that must include a varied approach aimed at the larvae and adults, with sanitation being key:

  • Ensure that floor surfaces are always clean and in good repair, because missing grout, cracks, and gaps in wall/floor junctions all tend to collect food debris and organic matter.
  • Regularly clean and flush those areas under processing equipment, as well as conveyor belts and other surfaces that can collect moisture and debris.
  • Keep in mind that moisture is conducive to fly breeding.
  • Find and fix leaks. If phorid flies prove to be the problem, there is most likely a leak in a sewer pipe, or other chronic moisture leak.
  • Remove wet dirt, which may support further breeding until it dries. If you can’t remove it, treat it with boric acid dust, which will prevent fly larvae from being able to live in it.

The author has been writing about the pest management industry for more than 30 years. Email him at

Editor’s note: This article originally appeared in a PCT e-newsletter titled “Targeting Small Flies,” which was sponsored by Rockwell Labs Ltd.