FLY SUPPLEMENT: Super Sleuth

Outside, flying insects play a critical role in maintaining the balance of nature, serving as an important food source for a wide range of animals. Inside, however, flying insects represent both a health threat and a nuisance, particularly when they involve food-handling and manufacturing facilities. That’s why flies, gnats, beetles, mosquitoes and other flying insects are serious business for PCOs providing pest control services to commercial accounts.

This article will use "real world" examples to illustrate successful strategies for minimizing such insect problems. After reading a description of an actual problem in a commercial facility, make a note of your recommendations and see if they coincide with the successful course of action implemented by our company’s service personnel.

THE CASE OF THE JUNK FOOD ‘JUNKIES.’ During a routine sanitation inspection of a food-processing facility in the rural South, an unexpected insect concern presented itself to the inspector. Dozens of dead beetles were discovered along the walls of the facility, with a particularly large concentration in the packaging area of the plant.

The beetles proved to be various types of diving beetles that live and breed in waterways (primarily lakes and ponds). Such beetles are attracted to outdoor lights on buildings, sometimes by the thousands. Sure enough, in this case, directly under exterior lights on the outside of the structure, piles of beetles — both dead and alive — were found.

The facility was located just a half-mile from a series of lakes and creeks. Sitting alone in the middle of a field, the facility’s bright mercury vapor lamps served as beacons for diving beetles, moths, mayflies, ground beetles and innumerable other insects. To make matters worse, the doors were left open to ventilate the building, including the area where freshly made potato chips traveled on a conveyor belt to be packaged into bags.

In addition, huge bins of old or unusable chips, flour and other foods were stored within 15 feet of the open doorways. The ground beneath the bins consisted of gravel and mud. In the July sun, these bins were swarming with flies, many of which entered the building. At a doorway used by truck drivers to access the building, an air door was installed, but the door was left propped open. Just inside, an insect light trap was located in a corner of the building, easily visible from the outside Interestingly, a mercury vapor lamp was located almost directly above the door and piles of beetles could be seen everywhere just inside the doorway, especially underneath the light trap.

In the processing area, a number of vats rested on a large platform. The area was extremely wet with standing water underneath the vats. The wall in a darkened area beneath the platform was covered with dozens of moth flies. By using a knife, wet cornmeal teeming with fly larvae could be scraped from beneath the base plates of the support posts.

Clearly, this food-processing facility had a serious pest problem. Based on the aforementioned description of the site, what would you recommend? Here’s what we did:

• The mercury vapor lamps in all exterior lighting was switched to sodium vapor lamps, thereby attracting fewer insects to the facility. Unfortunately, despite this step, given the location of the building, quite a few insects were still being attracted to the facility.

• Screen doors were installed on all doorways that remained open for ventilation purposes. Automatic screen doors were recommended for all overhead doorways. If screen doors were not used, plant personnel were required to keep all doors closed when not in use. All doors were equipped with tight-fitting weather strips.

• The insect light trap (ILT) inside the truck driver’s entrance was moved so it was not visible from the outside. The air door installed over that doorway was moved to an interior doorway between the receiving warehouse and the processing area.

• Additional insect light traps were installed in shipping and receiving areas of the warehouse since these were the primary entry points for flying insects into the building.

• The bulbs in the existing light traps had not been changed in several years, which meant they were attracting few, if any, insects. Plant personnel were instructed to change the bulbs annually in the spring.

• It was recommended that discard bins of food products be located further from the building. The bins should not sit in puddles of mud or water. Ideally, a large concrete pad should be poured, however, a thick layer of tightly packed gravel would suffice. Personnel were informed that the bins should be emptied on a more regular basis than the current weekly schedule. Empty bins should be cleaned immediately and not left to serve as potential breeding sites for flies.

• The cracks beneath the metal base plates of the platform support posts were cleaned out and dried using forced air and then sealed completely with long-lasting foam, thereby preventing the build-up of wet food debris under the base plates where it serves as a breeding site for moth flies.

By taking the aforementioned steps, the flying insect problem in the facility was corrected, resulting in a satisfied customer.

THE CASE OF THE ‘MODEL’ MOSQUITOES. A cosmetic-manufacturing facility located in the rural South regularly experienced flying insect problems. Mosquitoes proved particularly troublesome for employees indoors. Doors remained propped open during the summer. Huge wall vents were present along the front and west sides of the building through which air was drawn into the building for ventilation by large roof fans. Exterior lights surrounding the building contained mercury vapor lamps, attracting flying insects from a nearby lake.

The following was recommended to minimize the facility’s flying insect problems:

• Fine mesh screen was installed over each of the large wall vents to prevent as many insects as possible from being sucked into the building when the fans were operating. Nonetheless, the screens failed to stop the entry of midges and other tiny flying insects into the building. The right mesh size screen was determined by consulting with plant personnel and through trial and error.

• Exterior lighting was slowly switched to sodium vapor lamps.

• About 40 insect light traps were installed throughout the facility, except for where cosmetics were manufactured and packaged. (This area was a "clean room," which required hair nets, shoe covers and lab coats.) Here is what we recommended:

• Insect light traps were hung in the warehouse area in between every fourth or fifth warehouse door, perpendicular to the doorway. Located 12 feet off the floor, these traps primarily attracted nighttime-flying insects such as moths, beetles and midges.

• To capture daytime-flying insects and nighttime-flying insects making their way past the first set of insect light traps, additional traps were installed on walls throughout the forward part of the warehouse. The traps were located to cover an area no higher than 6 feet above the floor.

• Light traps were emptied every two weeks. Analysis of the trap catches revealed thousands of insects captured each week, including midges, horse flies, deer flies, yellowjackets, paper wasps and mud daubers.

• To solve the problem of mosquitoes entering the receiving and shipping areas of the warehouse, nighttime maintenance personnel were provided a non-residual aerosol product and trained in their proper application. These individuals would begin applying the aerosol treatment around 4 a.m., about two hours before the first shift. The frequency of applications was dictated by the incidence of mosquitoes and weather conditions.

THE ROAD-WEARY CRICKETS. During a routine cockroach service in a hotel kitchen, the service professional noticed many tiny, black beetles and crickets on several monitoring traps in the pastry prep area. The beetles were various species of ground beetles. Exterior lighting attracts crickets and ground beetles.

Further investigation revealed a doorway leading outside from the prep area. The door opened to a dumpster that had a standard 100-watt light fixture directly above the door outside. Kitchen employees, when asked, stated the door was often propped open at night. Here’s what we recommended:

• The exterior light bulb was switched to a yellow "bug" bulb to attract fewer insects.

• The door’s weather-stripping was improved, particularly at the bottom where it previously had no weatherstrip.

• Kitchen management was shown the traps were told of the problem. Employees were instructed to keep the door shut. A large fan was provided to ventilate that area of the kitchen so the door could stay closed.

SUMMARY. Flying insect control always begins with attracting as few insects to the building as possible. Good sanitation practices and proper lighting outside are critical. The next step is to exclude from the building the insects that are still attracted to the site despite previously mentioned efforts. Keeping doors closed, use of screens and screen doors and tight-fitting weatherstripping are keys. Inside, insect light traps, properly located, installed and maintained are critical 24-hour "sentinels" that capture most of the insects that do manage to enter the facility.

Remember, the key to successful control is that each flying insect situation must be analyzed on its own merits and the proper strategies employed based on the underlying causes of the problem.

The author is manager of technical services for Terminix International, Memphis, Tenn. He can be reached at shedges@pctonline.com.