7 things to consider when choosing an insect light trap

Harry Wood

A business that has a problem with flies or other flying insects should take an integrated approach to pest elimination. This includes looking at both prevention methods and improving practices such as food safety that can remove or reduce the food and food waste that attract them.

If you’re installing an insect light trap, the very first thing to consider is the difference between units that monitor and control a population. Monitoring units and control units look similar but perform different tasks on properties with varying risks of the presence of flies. 

As part of an integrated approach to fly control, an effective and essential step is to exclude flies and flying insects by monitoring traps, checking that your exclusion equipment and policies (door, fly-screens, door-policy education, etc.) are working as they should. Monitoring traps are usually glue board units that allow a technician or field biologist to count and record the number and species of flies that are captured on the trap. 

One of the essential components of fly control is to install an insect light trap (ILT) that removes flies from your environment quickly. The quicker we eliminate them, the lower the risk of fly-borne diseases.

There are many models on the market, all with various shapes, sizes, lamp types, and elimination methods. It can be difficult to know how to choose one that both effectively catches flies and is appropriate for your situation. Here we explain the most important factors to help you make a decision.

1. Attractiveness to flies


It may seem obvious, but it is vital to choose an ILT that attracts flies and other insect pests. Manufacturers make many claims about effectiveness, quoting brightness of the device, area covered, even number of species that their device will attract.

The UV lamps used are not all the same, however. Fluorescent lamps are manufactured in different ways with different compounds to alter the wavelengths emitted and with different manufacturing standards. They also fade quickly, reducing their effectiveness.

LED lamps can be manufactured to emit particular wavelengths and, while the intensity of light may seem important, it’s the relative intensity above ambient light levels that’s crucial for attracting flies. For this reason, wavelengths of light outside the visible light range are more attractive to flies than those that fall within it. What you need are high-attraction LED lamps optimized for a fly-control catch-rate to provide a higher level of efficacy.

2. Energy efficiency

Insect light traps are generally left on for many hours a day. This makes energy usage a significant proportion of the overall cost of ILTs. 

Look out for ILTs that monitor the surrounding environment and offer different settings for night and day. This lowers energy consumption, reducing running costs and your environmental footprint.

ILTs with low-energy LED lamps have a three-year life span (compared to fluorescent tubes that last about a year) and use less energy to run than a standard fly-killer – 10–33 watts compared to 45–90 watts. The lifespan and low-energy consumption reduce replacement costs and running costs, while also lowering the output of carbon emissions.

3. Area to protect 

Consider the size and shape of the room where you want to place an ILT and any objects in the rooms that will block the UV light. A restaurant kitchen or dining area will require a smaller model than a large warehouse or brightly lit supermarket fresh-food counter. 

Check the manufacturer’s rating for the area covered and how it is verified. Has an accredited lab verified the coverage of the unit? When choosing the number of units you need, make sure that all parts of the space to be protected have adequate light from an ILT unit – not just the total area – and that there are no hidden corners or spaces blocked by shelving, partitions, for example. 

Installation is the most important step when it comes to protecting an area from flies. ILTs should always be positioned between the place you’re trying to protect and the entry points. They need to be at the right height, away from other competing light sources, and not above food preparation areas.

4. Contrast with background

ILT studies show that insect catch rates are higher when the color of the unit contrasts with the wall behind it. This is because the high contrast makes the unit stand out more to flies. The two colors with the highest contrast are black and white, but, where aesthetics is important, you can choose other colors to achieve a similar effect. It doesn’t matter which color is on the wall or the ILT. It’s the contrast between the two that’s important.


5. Aesthetics

An ILT doesn’t have to be the typical white box with a metal grid in the middle that stands out like a sore thumb. You want to impress customers with your hygiene and service, so you need a better option. 

Restaurants and hotels, where aesthetics matter most, can choose unobtrusive and stylish models that blend in with their surroundings — to humans — and still stand out to the flying insects you’re trying to capture. 

ILTs with LED lamps, which offer lower glare, can be made slimmer and sleeker than those with fluorescent tubes because the lamp is only a few millimeters thick. Modern units can also have colored panels on the front to complement the background and hide the glue board, keeping flies out of view.

Consider, also, an ILT to match your different environments, with the flexibility to switch between monitor and control modes according to your needs.

6. Shape

A wide ILT is considered more effective at catching flies than ones that are circular or tall and narrow. This is due to the shape and orientation of the lamps in the unit and the shape of the light emitted. When lamps are orientated horizontally, wide, discrete bands of light are emitted, attracting flies. This likely happens because the bands mimic natural shapes of light, such as a horizon.

7. Servicing

There are two parts of an ILT that need to be replaced: the lamp and the glue board. The design of the unit will affect how easily it can be accessed and opened to replace the parts. Choose an ILT that is simple to open and service. 

ILTs used in food-handling businesses should have a glue board or roll rather than an electric grid so that flies are contained hygienically in the units and insect fragments aren’t scattered around the area by an electric shock. 

A technician will need to periodically replace and dispose of the glue board. This should form part of a servicing contract so a trained technician can hygienically replace parts without the risk of cross-contamination.

As mentioned earlier, fluorescent lamps need replacing yearly. This is due to the rapid degradation of the lamp. When the amount of light produced diminishes with time, it can compromise fly control. In laboratory tests, used lamps were less effective at catching flies than new lamps in the same unit. LED lamps, on the other hand, last three years at least. That means the cost of parts and servicing is lower for them.

And finally…

If you’re looking for the most appropriate fly-control for your business, make your considerations based on the units’ attractiveness to flies, energy efficiency, the area to protect, contrasting colors, aesthetics, shape, and service options. You may also want to see if you can find one range of units that suits your different environments.

For more information about ILTs or other prevention and control measures, talk to the experts in pest management.

Harry Wood
Harry Wood

Harry Wood is a Technical Content Specialist at Rentokil Initial, creating long-form content across the organization's online channels. A writer and editor for 30 years, Harry started out in an academic environment as an expert in tropical forestry and environment before moving into the IT, healthcare and medical technology industry and finally entering the world of pest and hygiene in 2015. A return to his roots writing about wood-boring insect pest, or is it boring Wood writing about insect pest?

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