Choosing the Best Outdoor Lights to Reduce Insects
By Pat Kelley, ACE
Like a moth to a flame, serious insect pest problems can begin with attraction to our outdoor lighting options. Most outdoor lights are going to have some insect attraction qualities, but the higher intensity (brighter) lights are more attractive than low intensity lights. The direction that a light shines can also have a big impact. An un-shielded bulb in a parking lot light will attract thousands of more insects than a shielded light that shines only downward.
From a pest standpoint, we know that the majority of light attracted insects prefer light in the spectrum between 300 – 420 nm. House flies seem to prefer a wavelength of ~365 nm while moths and beetles responded best to a slightly higher wavelength. The range of highest attraction encompasses a definite range on the light spectrum scale. It is important to ask light manufacturers for the wavelength specifications for their lighting options prior to purchase. If the lights that you currently have produce a wavelength that is in the area of insect attraction, perhaps you should explore
other options. In the case of outdoor lights, it pays to do your homework!
1. LED Lights – In general these are much less attractive to pests than other options.
2. High Pressure Sodium Lights – Great for parking lots but should be shielded from above.
3. Metal Halide Lights – The UV output is similar to the sun, negating some of its attraction to insects. Warning – Extremely high temperatures that require Teflon lenses!
Lights to Avoid
1. Ultra Violet (UV) Light – Black (UV) lights are highly attractive to insects and are best kept in insect light traps or in teenager’s bedrooms.
2. Fluorescent Lights – Produce lots of UV light that attract pests. Use only indoors.
3. Mercury Vapor Lights – These lights are so attractive to insects that they can be used to pull insects away from a building if they are placed 30 feet or more away!
4. Incandescent Lights – Common light bulbs are good for indoor use only.