For too long, the humble Insect Light Trap (ILT) has been relegated to a simple commodity—a glowing box installed to meet a contract requirement.
However, as industry veterans know, the difference between a compliant installation and truly effective fly control lies in a deep understanding of entomology, technology, and placement strategy.
This crucial distinction was the core of a recent, must-watch interview on Pest Posse TV’s “Beyond The Glow – How UV Light Traps Work.”
Host Foster Brusca, a seasoned PMP and self-proclaimed top-seller of fly traps in his career, lamented the lack of conversation and training surrounding ILTs. He rightly challenged the industry: there is far more to fly control than just selling a UV light device; there’s a need for PMPs to utilise these tools to their maximum potential.
To address this gap, Brusca sat down with an unparalleled expert: Dr Bill Robinson, a renowned PMP Hall of Fame Entomologist. Dr Robinson’s background is formidable, including thirty years of teaching and researching pest control as the Director of the Pest Control Research Centre at Virginia Tech (mentoring 22 PhD students!) and twenty years dedicated to pump design, quality control, and light trap development at B&G. His insights, particularly his work now with Bentz Jaz USA on advanced ILT designs like the FLYght Duo, offer the definitive roadmap for PMPs looking to catch flies “smarter, not harder.”
This blog post compiles and expands upon the critical takeaways from this interview, providing you with the science and strategy to transform your fly control service.
1. The Deep Science: Why Flies See and Seek the Glow
To master fly control, you must first understand housefly behaviour and vision.
What exactly are they looking for, and why does our technology work?
A 90-Million-Year-Old Evolutionary Cue
Dr Robinson provided a fascinating historical context: houseflies first associated with lactating animals approximately 90 million years ago. This co-evolution led to a unique biological trait: the housefly is the only insect capable of efficiently breaking down the milk sugar lactose.
This ability is directly linked to their visual appeal. Houseflies are instinctively drawn to the light of 480 nM wavelength, which is the light that reflects off milk protein. In nature, houseflies are outdoor creatures, attracted to UV light bouncing off surfaces in their environment. When humans domesticated cattle more than ten thousand years ago, houseflies naturally followed the cattle indoors.
Understanding the UV Source
The effectiveness of an ILT is entirely dependent on the quality and intensity of the UV light emitted.
- Fluorescent Tube Mechanics: In normal fluorescent lights, an internal coating prevents the UV light (emitted by the mercury vapour inside) from escaping. In traditional UV fluorescent tubes, this coating is absent, allowing the UV light to pass through the glass. However, the mercury used to generate the UV light in these tubes does not last long, leading to a steady decline in trapping efficacy over time—a hidden cost often overlooked by PMPs.
- The Power of Reflection: The interview stressed that flies are primarily attracted to UV light bouncing off surfaces. A higher-wattage UV light may attract more flies not just because the direct light is brighter, but also because it generates more reflected light off the walls and interior components of the trap. This principle—the draw of reflected light—is fundamental to modern UV LED Traps.
2. Mastering ILT Placement: Smarter, Not Harder
Once the science is clear, the next step is applying it through intelligent trap placement. Foster Brusca and Dr Robinson emphasised that the biggest mistake PMPs make is placing ILTs based on convenience rather than science.
The Factors Governing Placement
ILT placement is a multi-faceted decision, influenced by the species, the environment, and the structure’s function:
- Species Focus: First, determine which species you want to attract. While houseflies seek reflected UV light, other species may have different preferences. It’s also important to know that ILTs are effective for attracting and monitoring other common pest species, including moth flies and phorid flies.
- Avoid Competition: The most critical rule is never to let the trap compete with natural or other light. The best location is a dark corner away from direct or reflected sunlight. Placing an ILT where sunlight hits or near a bright window will effectively render it useless.
- Mechanical Controls: The functioning of other pest controls, such as air curtains at doorways, must be considered. An ILT placed too close to a functioning air curtain will have its attractive light and fly-catching function severely compromised by airflow.
- Logistical Limitations: Real-world room limitations, such as the location of the nearest plug point, often influence light trap placement. PMPs must strive to balance these limitations with the scientific principles of attraction.
- Serviceability: A common, yet costly, error is placing the trap too high. Placing an ILT in a way that forces technicians to use ladders to service the glue board increases service time, raises safety risks, and may lead to less frequent or thorough maintenance. A height of around 4 to 5 feet above the ground often strikes the best balance for housefly attraction and PMP access.
3. ILTs as Diagnostic Tools: Beyond the Kill
For PMPs to truly deliver value in commercial accounts, they must shift their perception of an ILT from a simple “bug zapper” to a sophisticated monitoring and diagnostic tool.
Dr Robinson strongly recommended that technicians perform a meticulous analysis of glue boards rather than just performing a quick, rote replacement. Glueboard analysis is where the service moves beyond the Glow to become data-driven.
Glue Board Analysis: Your Eyes and Ears
The composition and location of the catch on a glue board can provide critical intelligence:
- Door and Air Curtain Function: A sudden, heavy concentration of houseflies or specific perimeter pests on a glue board near an entry point can directly indicate an issue with door opening/closure protocols or the malfunction of an air curtain.
- Species Composition: Identifying the ratio of houseflies to, for example, phorid flies or moth flies, helps the technician pinpoint the breeding source. Are they coming from organic buildup (phorids/moth flies) or the exterior perimeter (houseflies)? This analysis dictates the necessary action.
By analysing, questioning, and then initiating appropriate action, the technician provides a proactive, consultative service rather than a reactive one.
4. The Next Generation: The Power of Reflective Technology
Modern technology is rapidly evolving to capitalise on these principles. The interview featured the FLYght Duo as a case study in next-generation ILT design, emphasising that the future of ILTs is in UV LED Traps that maximise reflected light.
The key features that distinguish this approach are:
- Targeted Reflection: Unlike traditional traps where UV reflection may be accidental (e.g., bouncing off the glue board), the FLYght Duo is explicitly designed to utilise a bio-visual enhancer to reflect UV light efficiently. This dedicated reflective component creates a powerful, attractive signal.
- Subtle Power: The FLYght Duo is intentionally not overly bright, unlike other ILTs. Its effectiveness comes from the quality of the reflective light it emits, which is perfectly tuned to the housefly’s 480 nM visual sweet spot, making it highly effective without being visually obtrusive in a food facility or public space.
- Adaptability and Service: The unit’s lightweight design makes it uniquely amenable for repositioning to suit changing requirements, pest pressures, or seasonal needs within a monitored space. This agility helps PMPs maintain peak performance.
The future of professional fly control demands that PMPs move past simply selling a box that glows. It requires leveraging the science of Dr Bill Robinson and the strategic approach championed by Foster Brusca: understanding housefly behaviour, executing meticulous trap placement, and utilising the ILT as an active glue board analysis tool.
With new UV LED Traps built on the principles of UV light reflection now entering the market, like the FLYght Duo—which made its US debut at NPMA PestWorld 2025—PMPs have the tools. The only thing left is to apply the knowledge and finally move fly control beyond the glow.