Seeing dozens or even hundreds of bugs circling a nearby street lamp is a common summertime sight. It's no secret that many flying insects are attracted to artificial lighting. If your building has any nearby lighting, the bugs it could potentially attract could become a nuisance. The following not only explains why this happens, but also how you can keep interested pests at bay.

What Makes Lights So Attractive for Insects?

There are plenty of theories on why some pests are so drawn to artificial lighting. Some insects follow light sources as part of their internal navigation. The moon is a reliable nighttime light source, as it's always emitted at a constant direction and angle. Not only do artificial lights overpower natural moonlight, but the omnidirectional nature of a typical light bulb can easily throw a bug's navigation into disarray.

Some insects often mistake light sources for flowers that normally reflect UV light, so a nighttime search for food often results in a run in with a nightlight. The warmth emitted by some lights can also provide a secondary attraction for others. A few insects may even rely on light as a way to avoid obstacles, often mistaking a bright light bulb for a completely clear opening.

So it's little wonder why bugs seem to fly in circles around light fixtures - they're usually lost and confused about where they're supposed to go.

Which Lights Attract Insects the Most?

Mercury vapor lights tend to be the most attractive to flying insects. Other types of lighting that fall within the 450 to 500 nm range - the bluer end of the UV spectrum - are also highly attractive to insects. Traditional tungsten incandescent lights can also attract their fair share of insects, not only because of their light but also due to the heat they generate during operation.

How to Reduce Light Attraction

Switching your outdoor lighting from mercury vapor to high pressure sodium vapor can discourage insects from congregating around light fixtures. Sodium vapor lights are typically yellowish in color, whereas mercury vapor lights produce a whitish blue hue that's more attractive to insects. Other types of lighting that emit UV light in the 575-600 nm range are also less attractive to insects.

LED lights are also a good alternative that aren't as attractive to light-seeking insects. However, you should make sure you're not using LED lights that produce UV light in the 450 to 500 nm range. Find out more here.