Lab · Technology

Insect light traps

Quick answerVerified September 26, 2026

What is insect light traps?

Wall- or ceiling-mounted units that draw flying insects with ultraviolet light, then hold them on a glue board or kill them on an electric grid. In food plants and kitchens they catch flies and night-flying insects such as moths that got past exclusion. They add to sanitation and exclusion. They do not replace either.

Reviewed by LTK editorial team

Where it fits

Food-handling areas where insect fragments are the real risk. Glue-board traps were developed because electrocution blew visible fly particles away from the trap and also produced small airborne particles that could carry bacteria and viruses. In a controlled test, flies sprayed with bacteria or a virus released about one in every 10,000 of those microbes when electrocuted. A glue board holds the insect whole.
Low wall mounting along fly routes. In open poultry houses, traps with the bottom edge about 10 cm above the ground caught 10 times more flies than traps mounted 1.5 m up. Evidence also suggests floor-level traps out-catch traps at 2 m, though the review says more work is needed. The UV-safety study describes low wall-mounted units as the accepted layout for flies and night-flying insects, with ceiling-hung units useful where night fliers such as moths are the main concern.
Bottlenecks and flyways away from where people work: next to doorways, in vestibules, and along the route between dumpsters and the areas being protected. That was where the UV-safety researchers found traps installed. Measured UV exposure at realistic distances was well below human guidelines, and no unit exceeded the 8-hour UV-A limit beyond 60 cm.
Accounts that need a serviced, dated catch record. The house fly review describes the usual commercial service as monthly: replace the glue board, check operation, clean the unit, and replace the bulb every six months. Our read: the used glue board is a record of what was flying there since the last visit, and that is what makes it useful for audits and trend checks.

Where it does not

This is the part the brochure leaves out, so it is the part worth reading.

Over a food preparation area, whatever the trap type. The FDA Food Code (6-202.13) requires electrocution or stun devices to retain the insect inside the device. It also requires all insect control devices to be installed away from food preparation areas, so dead insects and fragments cannot fall or be thrown onto exposed food, clean equipment, utensils, linens or unwrapped single-use items. The code restricts grid units. It does not ban them, despite what trade copy often says.
High above or facing an entry door. A trap mounted high over a restaurant entrance tends to draw flies to the door, where they may get inside. Put the unit where it pulls insects away from food and toward the trap, not toward the opening.
As a substitute for sanitation and exclusion. The Food Code annex calls electrocution devices supplemental to good sanitation, and the house fly review puts keeping flies out first: air curtains, screens, slat doors and closed entry doors. In urban sites the flies usually come from somewhere else, so a unit that keeps catching is pointing you at a door or a source. It is not the fix.
Paying extra for glue-board add-ons or colours on the promise of higher catch. Glue boards with pheromones or other attractants added showed no benefit in laboratory studies, and most climate-controlled businesses have five to eight complete air changes an hour, which clears most odours anyway. In field studies, black glue boards cut fly catch by as much as 50% compared with white.
Buying LED units on published efficacy. As of the 2021 review, the authors could not find published accounts of successful LED traps. Most evaluated units use fluorescent blacklight tubes. Lamps are replaced on a schedule because output is highest when they are new; the UV-safety study measured freshly installed lamps as its worst case for that reason. We found no peer-reviewed figure for how fast output falls, so follow the manufacturer's replacement interval.

Sources

See what members use