[Fly Control] Insect Light Traps — a Dual Tool

Although the primary purpose of insect light traps (ILT) is just that — trapping insects to eliminate them in your plant, the traps can be beneficial for plants not only as an effective tool for insect management, but also as an efficient source of light, consideration of which should be made in their purchase.

While there have been design improvements with ILTs through the years, there has not been a great deal of technological development or innovation, and, in fact, some industry experts believe that there should be a great deal more scientific research and authentication of the “facts” by which the lights are marketed. Even these experts, though, agree that ILTs do provide an effective tool for the control of flying insects, and hold significant value in insect control in plants as part of an integrated pest management plan that includes exclusion, prevention, sanitation and chemical control.

MANAGEMENT TOOL. FDA’s 2001 Food Code sets guidelines for the use of insect light traps as they relate to food safety, stating that the devices must be designed to retain the insect within the device, and that ILTs shall not be located over a food preparation area and that dead insects or fragments are to be prevented from being impelled or falling onto exposed foods or food-contact surfaces or items.

Not only is it important to keep dead insects or fragments out of the food, but also because, as explained by Dave Poling, Business Director for Whitmire Micro-Gen, “You don’t want to put anything that’s going to attract flies right over where you are producing food.” 

The use of ILTs in food plants has  increased in recent years due to changing regulations, Poling added, including the phase out of methyl bromide, which has had an effect primarily on control of stored product pests. In the past, pest management professionals would conduct methyl bromide treatments in food plants, which would eliminate “every living being, every animal in the facility,” he said. “You take the population down to zero, and it’s easier to keep it down.” There always have been light traps, he added, but now that plants don’t get populations down to zero, they need more continuous protection to keep populations down. “You can build a continuous 24/7 protection with light traps,” he said.

Craig Martelle, now AP&G’s vice president of professional products, previously had been a sanitarian for Kroger Foods. He described a placement trick incorporated in Kroger’s plants was placing yourself at the point of potential ILT placement. Stand with your back against the wall, look straight ahead and note everything that you can see across your line of peripheral vision. If you can see any doors or windows, then the external flies will be able to see the light trap from outside as well. Place the trap at the points where the fewest doors or windows are visible (ensuring that it is away from food sources).

This strategy also works for placement because it sets the proper height for the ILT, which Martelle said is always a question. Understanding that flies are attracted to food sources, they will spend the majority of time in areas where they are most likely to find food, which will generally be from floor level to about six feet.

As part of your IPM program, ILTs can provide both control and monitoring, said Jack Harris, marketing director for Insect-O-Cutor, and author of chapter 8, Insect Light Traps, in Insect Management for Food Storage and Processing (AACC International, 2006). A strategic approach involves:

1.) Identify the need. Is there a contamination risk? Is there open product or process which flying insects could contaminate? If so, you need to consider what and where this risk is and how you can intercept the insect to prevent the contamination, e.g., through the placement of traps at major exterior entry and exit points, loading docks and trash areas.

“If you are considering insect light traps for your facility, do look at your loading docks and what areas are most attractive,” Harris said. “(And ILTs are) one tool that can help with your insect management … with both control and monitoring.”

2.) Determine type and placement. In addition to the strategic points noted above, ILT placement should be determined by the specifics of the plant and insect sightings. Placement in a warehouse area is a bit more standard, Poling noted. The traps should be placed at 25- to 50-foot intervals, with additional attention given to location of dock doors and other plant entryways. 

In addition, Martelle said, you need to consider visual obstruction in placement. “If there’s more equipment, you need more lights because it’s an obstructed view,” he said. For example, if a large oven runs down the middle of the plant, one light on one side will not suffice to manage flies regardless of the room size.

It is best to work with a professional, through the manufacturer, distributor or pest management service, to ensure you are selecting the best type, style and number of lights for your facility. Because there are a number of considerations to make in selection, it is best to involve all applicable managers — from quality assurance to purchasing. “If you can get all parties involved, it makes a smarter buying decision,” Harris said.

In addition, always remember your trap locations do not have to be final. You can locate a trap where you believe it will be beneficial, but as Harris said, “If it’s not working, you can move it.”

3.) Monitor your plant. “The monitoring aspect of the light trap can be very beneficial,” Harris said. Once the ILTs are set, if a trap suddenly starts collecting a lot of insects, you know there is a problem in that area. You may need to incorporate other management tools, such as exclusion, sanitation or chemical control, to eliminate the source of the problem, then retain the ILT for continual management and monitoring.

While there are industry-accepted placement strategies for ILTs, there will always be exceptions, and proper placement should be based on the specifics of your plant. David Gilbert, president of Gilbert Industries, cites the strategy of placing ILTs low for best house fly catch as an example. In a field test his company ran, ILTs were placed high on the wall. “All of a sudden we were catching more house flies in the higher traps,” he said, and after investigating, they realized that the plant had ceiling heaters blowing toward the floor. The warmth attracted the flies to the higher levels, and thus to the higher light traps.

Knowing where insects have been sighted is as important to placement as is accepted industry strategy.

While Gilbert knows the value of light traps, he said many of the established strategies and truisms of the lights are based on non-validated field experience rolled down through the years, rather than actual scientific research. “So much of the business is based on the bottom line and science gets pushed to the bottom,” Gilbert said. “I’m going to challenge the industry to become more scientific.”

For example, while Gilbert understands the thinking behind the recommendation for bulbs to be changed annually, he said this is based more on logic than scientific study of the longevity of effectiveness. “It really is common sense not scientific research,” he said. But because the bulbs do lose energy over time, it is logical to replace them in the spring — the start of flying insect season — so they will be at their peak efficacy.

Another example Gilbert references is an assertion that electrocutor-type traps “spew out insect parts.” To dispute this, Gilbert cites the result of tests conducted by Donald E. Weidhaas, retired director of the USDA, and Phillip B. Morgan, 30-year USDA research entomologist, which studied the damage to and spread of house fly body parts as a result of electrocution in light traps (Gilbert 601T). The research found that the majority of flies showed no body damage from electrocution. When flies did lose body parts, it was of the legs or wings, all of which were found within the trays or within six inches of the ILT. White sticky panels placed in 15 locations in the room and examined by eye, hand lens and microscope showed no fly body parts or evidence of contamination away from the trap.

Even if the claim of airborne micro-particles were true, Gilbert added, if you had no light traps, you’d have not just micro-particles flying around but live flies flying around. “You’re still a whole lot better off with micro-particles than a whole fly,” he said. Glueboard and electrocutor traps are not much different in efficacy, he said, “There are places for both of them.”

AS A LIGHT SOURCE. “When you think of a bug light, you don’t think about what kind of power-pack is in it,” Harris said. But maybe you should. “Most of the energy consumed in this nation is consumed by lighting,” he said, so when you look at insect light traps, you should think of them not only as pest management equipment, but also as lighting fixtures. 

The key components of an ILT are: cabinetry, killing/trapping mechanism, light and power-pack, with some older styles also having fans to suck the insects into a bag. It can be argued that the light — which is the basis for attracting the flying insects — is the most important component of the ILTs. But there has not been a great deal of technological innovation in the fluorescent bulbs since the 1950s or 1960s, Harris said, although the Energy Policy Act (EPAct) of 1992 brought developments in both the ballast and bulb size options to enable a more energy efficient unit.

“Years ago, everyone used a magnetic ballast,” Harris said. The downside of such technology was that it required significant amounts of energy to light the bulb, and it would continue to supply the amount of energy even though once on, the bulb required significantly less. In reaction to EPAct, an electronic ballast was developed which would enable surge control, putting out only the amount of energy required for each stage of the lamp’s functioning, and resulting in a 26 to 40 percent reduction in energy usage, Harris explained. “EPAct impacted ballast manufacturing because everyone knew it didn’t require a steady surge of electricity,” he said. 

As a result, most  market leaders converted to electronic ballasts, he said, which provides users not only with energy-efficient options, but also equipment of lighter weight and quieter operation.

Other changes in ILTs are primarily based on design improvements, both aesthetic — adding decorator touches to face plates and making the glueboard/trapping area less visible — and functional — simplifying access and serviceability. Poling also sees the market moving more toward glueboard units, with many of their customers preferring these in food processing or preparation areas then converting warehouse and other areas for consistency of service.

One caution Martelle asserts when using glueboard ILTs is regular changing of the board. He has seen fly boards which have been in the trap for so long that the flies have dried on them, he said. The time between changes will again be based on plant conditions, with more frequent change required during fly season. During the season, glueboards should generally be changed once a week, while plants can often wait a full month during the winter. But even more important than time is the accumulation of flies on the board. It is really a sanitation issue, he said, and inspectors will write up facilities based on number of flies.

If the number of flies being caught gets excessive, such as filling on a daily basis, the plant should most likely be implementing additional methods to stem the flow, such as increased sanitation, chemical application where allowed, or simply the shutting of doors. “If they are getting an excess like that, it is because somebody, somewhere is doing something wrong,” Martelle said.

Though primarily for and effective in integrated pest programs for defense against flying insects, ILTs can also provide a significant source of light for a plant. Taking all elements into consideration when purchasing and placing the traps will provide a plant with the best all-around program. 

Lisa Lupo is staff editor of QA magazine.