Insect light traps (ILTs) are one of the most underutilized, misunderstood pest management devices in food processing facilities. Most of the misuse comes from a lack of understanding of their purpose: Their most critical function is to be a monitoring, not a control device.

ILTs can never replace a closed door or screened window, but many facilities have their devices positioned in such a way that the primary function would appear to be intercepting insects as they enter the facility.

The ABCs of ILTs

We all understand the basics of why ILTs are in facilities, but using them to their fullest is often overlooked. We place these devices to capture flying insects before they can contaminate product, but there are many nuances to their placement and maintenance.

A good ILT plan and program should include the following:

1. Adequate placement and size to accurately assess the flying insect activity. No two facilities are the same. A careful assessment of the influencing factors must be considered before determining the size and numbers of ILTs to be placed. These factors would include such items as:

•Are the surrounding types of facilities conducive to flies?
•Is the exterior landscaping or surroundings conducive to fly habitation?
•How tight is the facility construction?
•Are the doors, vents and screens maintained in a "fly tight" fashion?
•Has staff been trained to report maintenance issues and close open doors?
•What kind of exterior and interior lights are competing against your program?

2. Once the influencing factors have been assessed, placement of the units can be made. Remember that bigger is not always better. Keep the following in mind when placing ILTs:

•Install lights no higher than eye level. This is where most flying insects travel, and it makes maintenance of the lights more practical.
•Make sure that no ILT is installed where the light may face an open door. Even though doors are supposed to be closed, they do get left open. Ultraviolet (UV) light is highly attractive to most flying insects. They will be drawn into a facility when lights face the exterior.
•Make sure there are no strong air currents from fans or other sources near the ILTs. Air movement significantly alters flying insect flight patterns. If a fan is near an ILT, it will not perform as a good monitoring tool.
•Make sure that adequate placements are made in areas most likely to have failures. Even though influencing factors have been assessed and corrected, accidents happen. Additional light placements are always a good practice in shipping/receiving, employee entrances/locker rooms, garbage/recycling and mechanical rooms.
•Never place ILTs of any type over or near open food packaging. It increases the potential of insects that are attracted toward the UV light unintentionally ending up on or in a food source. In addition, there's a potential for accidents to happen when catch trays/glueboards in ILTs are being emptied/changed.

3. Make sure that all ILTs are part of a preventative maintenance program. Many ILTs get placed and forgotten. It's critical to maintain ILTs to ensure the effectiveness of your strategies. The following should form an integral part of your ILT program:

•Weekly checking and documentation of insect numbers and types during months when flying insects are an issue. The type of insects found in an ILT can tell you a lot of what is taking place around your facility. For example, if you suddenly are collecting large moths, there's a good chance night staff are leaving doors open. A minimum of monthly checking in "off-season" months will continue to monitor for any internal issues such as certain stored product insects.
•Ensure that units are kept as clean as their surrounding environment. Cleaning the grids is fine to keep them working effectively, but these units should be a part of the facilities Standard Sanitation Operating Procedures (SSOPs) to ensure they are being maintained in a manner in keeping with the environment.
•Make sure that bulbs are maintained. These bulbs should be replaced, at least, once per year — and every six months in regions where insect activity never ceases. Make sure that all bulbs are shatterproof, and that the coatings used permit adequate UV permeation. Date new bulbs when replacing.
•At least once a year, the lights should be dismantled and thoroughly cleaned to ensure that all insect parts that might be trapped inside small internal cavities are removed. In rare cases, certain insects will infest other dead insects and create an internal infestation.

ILTs are an essential part of any pest management program, but it's important to recognize their limitations. Their greatest asset is telling us where our failures exist. They should only be considered an additional set of eyes that help us to assess what is happening within the facility. Once people wrap their heads around the fact that ILTs are just another monitoring tool, their true value can be appreciated.