6 min read · By Nathan Clarke
UV Wavelengths and Mosquito Attraction, Explained
365nm, 395nm and three-band lamps: what the numbers on a bug zapper box actually mean for how many insects you catch.
The numbers on the box
Bug zapper listings advertise wavelengths in nanometres: 365nm, 395nm, sometimes a vague 'three-band UV'. A nanometre figure describes the colour of light the lamp emits, and insects respond very differently across that range.
Below roughly 400nm, light is ultraviolet — invisible to us, highly visible to many insects. That is the entire premise of the product.
Why one band is not enough
Different flying insects peak at different wavelengths. A lamp tuned to a single band is efficient at pulling in the species that peak there and close to useless for the rest.
Multi-band lamps hedge. By emitting at two or three points across the near-UV range, they overlap with the sensitivity peaks of more species — including the ones that carry disease rather than just annoy you.
Light is a secondary cue for mosquitoes
It is worth repeating: mosquitoes hunt primarily by carbon dioxide plumes, heat and skin odour. Light gets them into the neighbourhood, not onto the grid.
This is why lamp quality and placement are inseparable. A three-band lamp two metres from where you sit does more than a three-band lamp mounted on the far fence, because it intercepts the flight path rather than competing with you from a distance.
Brightness is not the same as attraction
A brighter lamp is not a better lure. A high-lumen white LED is very bright to human eyes and unremarkable in the UV range that matters. Some devices split the job: UV tubes for attraction, plus a separate white LED array for actual lighting.
Those two-in-one lanterns are the practical sweet spot for a deck, because you are not running a camping light and a zapper as separate devices.
Lamp lifetime and running cost
Traditional fluorescent UV tubes degrade — a bulb rated for 2,500 hours has lost meaningful output long before it fails outright, and a fading lamp quietly stops attracting anything. UV-LED units rated for tens of thousands of hours sidestep the issue.
When comparing two units, work out the cost of replacement bulbs across two seasons. It regularly flips the ranking of the cheapest options.
What to look for
Prefer a lamp that states its wavelengths explicitly, covers more than one band, uses LEDs rather than replaceable tubes, and separates its attraction light from its area light. Treat unlabelled 'UV light' claims as a warning sign — a manufacturer confident in its lamp publishes the numbers.
The zapper that topped our 2026 test
Chemical-free, rechargeable and currently 50% off on the official site.