“Small flies are basically red flags with wings. If I see a small fly in a restaurant that tells me there may be an issue with sanitation in the back of the house.” That’s the assessment of Tom Dobrinska, an acknowledged small fly control expert based in Elmhurst, Ill. Dobrinska, technical service manager for Anderson Pest Solutions, says that health concerns associated with the various species of small flies are usually underestimated. “They may take a backseat to large flies, but keep in mind this fact: they are mechanical vectors of bacteria. Imagine unsanitary conditions where they lay their eggs, breed or feed. Small flies can physically transport some potential diseases from those areas. So don’t just ignore them.”
He identified the several species of small flies that are on the pest control industry’s “most wanted” list and suggested effective control measures:
Red-eyed fruit flies and dark-eyed fruit flies, also known as Drosophildae, the most common of small fly species can be found infesting restaurants, homes and other buildings. They are each one-quarter inch in size and are usually attracted to decaying fruits, vegetables and other organic matter. One source of such material can be spray-washed plant floors. The spraying action can force lots of organic matter to floor drains. Not regularly cleaning drains and floor cracks, crevices and corners could create feeding and breeding sites. The red-eyed fruit fly seems to prefer fresh organic matter, while its dark-eyed cousin can be found in more putrid conditions. They can reproduce where wet or damp organic matter exists and evolves from larvae that need moist organic matter in order to survive.
Drain flies, also known as moth flies, also known as Psychodidae, are small, dark, fuzzy, moth-like creatures with heart-shaped wings. Scales on their wings often resemble moths. They are not exclusive to drains but often can be found in sump pumps or sewer lines, as well as in washroom floor drains. These pests breed in polluted shallow water or the scum that you can often find around drains. Adult drain flies can be stationary during the day, but at night can be seen zipping through the air over sinks, drains and other breeding areas. They prefer highly decayed matter, such as that found in sewage treatment areas and lines.
Phorid flies, also known as humpbacked flies, also known as Phoridae, are sometimes considered the most dangerous, most troublesome of the small fly species. They are very small, usually an eighth of an inch long, and usually flit about in a zigzag pattern. They more or less differ in appearance from other small flies by the "humpback" shape of their abdomen. They are usually tan to dark brown in color and have dark eyes. Phorid flies are a serious problem for food-manufacturing facilities and an infestation can possibly come from a sewer break under a building. They will often feed and breed in moist decaying matter. Like the other small fly species, they are frequently found in unsanitary areas and often transmit disease by carrying germs and bacteria onto food products and sterile surfaces.
According to Dobrinska, effective small fly control means finding and eliminating all sources of potential infestation. Finding the breeding areas is key in a total control effort.
“If Phorid flies are breeding in garbage, moist soil or organic decaying matter, the only way to get rid of them is to remove the decaying matter. Spraying the infested areas with a pesticide will not provide control. It’s important to know that only proper drying and proper sanitation in these areas will provide the control you need.”
Dobrinska maintains that almost any type of flytrap will help to trap Phorid flies, and adds that using aerosols containing pyrethrums is also very effective at killing adults.
“The biggest likely infestation source in a home is in fermenting or rotting fruit and in trash cans that haven’t been dumped recently. Another possible source is a sink, bathtub, shower or floor drain with a layer of slime.
“In restaurants and bars, sources could include spilled beer, soda, and food that hasn’t been adequately cleaned. Look for wet areas under dripping pipes and refrigeration equipment, garbage containers, and discarded bottles and cans. Look for small flies flitting about above the bar or in the kitchen.”
He reiterated the fact that small flies are best controlled by persistently locating and eliminating the source of the infestation.