FLY SUPPLEMENT: Small Flies Cause Big Problems

Small flies are replacing cockroaches as the premier pest in restaurant and food-handling accounts across the U.S. How your technicians and other personnel manage the problem will be the difference between a satisfied customer and or repeat callbacks to a never-ending problem, said Steven A. Kells, Ph.D., B.C.E., technical support manager, Abell Pest Control Inc., Toronto, Canada. Kells spoke on his experiences with fly control at the 2001 Purdue Conference.

There are key features to a fly infestation that the technician must consider to ensure rapid and complete control. He must recognize the adult flies as a symptom of a larger problem and eliminate the fundamental source: the accumulation of decaying organic matter, a combination of water, food or microbes (bacteria, fungi or yeast), that provide food for fly larvae.

Kells said controlling flies is relatively simple: What pest management professionals need to do is remove the decaying organic matter and break the fly production cycle. However, the tricky part is finding the food source responsible for the fly infestation. This relies heavily on proper fly identification and a thorough inspection of all areas within a structure.

"Different fly species will be attracted to different types of organic matter and the faster you find the source, the easier it is to control any fly," Kells said. He gave some "general rules of thumb" for PCOs to remember when identifying several flies that commonly infest restaurants and food production areas.

FRUIT FLIES. Fruit flies typically search for food that is relatively fresh, meaning less than two weeks old. Fruit storage bins, underneath bars in restaurants, garbage disposal drains, sugar water and soda dispensers are popular fruit fly infestation sites.

Garbage cans also factor into fruit fly infestations because many restaurants leave their garbage cans inside the building for security reasons. However, allowing garbage to site overnight inside the restaurant kitchen causes liquid to settle at the bottom and becomes another infestation site, Kells said.

In addition, recycling bins also serve as a prime infestation area for fruit flies because unwashed soda cans are left unattended until the bins are full. "Often there’s a main collection site and various smaller recycling bins throughout the building for convenience. This is an easy way for the infestation to spread throughout the building," Kells said.

MOTH FLIES. "These flies go after food that’s been around for awhile, and it’s generally unidentifiable black goop by the time it appeals to moth flies," Kells said. Moth flies generally "hang out" with their wings spread around their food source, making them easy to distinguish from fruit flies, which constantly fly around their food source.

Grout lines and cracked tile or plastic in food preparation areas are popular places for moth flies to infest. "Basically, any gap where food can get caught and is difficult to clean off will be a place these flies look for food," Kells said.

PHORID FLIES. Kells has an easy way to get a customer to distinguish between a fruit fly and a phorid fly: Have him nudge the fly with his finger. "If it immediately flies away, it’s a fruit fly. However, if it hops before it takes off, it’s probably a phorid fly," Kells said.

But there is an exception to the rule: "Any young adult fly that has recently hatched from its pupae will hop before taking off because it’s relatively new to flying," Kells said.

According to Kells, "Phorid flies eat the material that moth flies are afraid to touch. Most likely, the food has decayed beyond recognition and is generally found in drains as well as cracks and crevices," he said.

Kells also disclosed a little-known fact about phorid flies: They are also called coffin flies because they’re known to infest coffins inside mausoleums.

The phorid flies’ ability to infest tight places, such as coffins, also allows them to infest areas beneath a slab foundation. Grease traps and sewage system pipes are popular places for phorid flies to gather under a foundation.

FUNGUS GNATS. Fungus gnats infest areas near the soil where fungus has grown, such as near freezers, doors, windows and on over-watered indoor plants. "I usually finds fungus gnat larvae near gaps in windows and doors and they travel to their food source from there," Kells said.

STRATEGY. Kells summed up his strategies for eliminating a fly infestation:

• Most flies tend to breed when their area is quiet. Morning may be an ideal time for an inspection.

• Perform a diagnostic fogging. If it is difficult to identify a source of infestation, apply sticky traps, then fog the building.

• Get the customer to remove the flies’ food source by cleaning, removing products from the location or sealing the products attracting flies.

• After the above steps have been completed, remove the adult flies with the method the technician and customer feel most with.

The author is Internet editor for www.pctonline.com. She can be reached at apaskiet@pctonline.com.