Black lights, also known as UV lights or ultraviolet lights, emit wavelengths of light that are invisible to the human eye but can be seen by some insects. Many people wonder if using black lights can help repel or trap unwanted bugs in their homes. The effectiveness of black lights against bugs depends on the species. While black lights attract some insects, they repel or have no impact on others. Understanding how different bugs react to black light can help you decide if using a black light bug zapper or bug trap is worthwhile.
How Black Lights Work
Black lights emit ultraviolet (UV) wavelengths of light between 320-400 nanometers on the electromagnetic spectrum. This range is classified as UV-A light. The light appears purple or violet to humans, as our eyes cannot fully detect UV wavelengths.
Standard white lights, like LED or incandescent bulbs, give off little to no UV light. They instead emit visible light wavelengths between 400-700 nanometers.
When objects are illuminated with UV light, they display different visual properties than under visible light. Some minerals and organic compounds naturally fluoresce by absorbing UV wavelengths and re-emitting longer, visible wavelengths. This causes them to glow vividly under a black light.
Many spider webs and insect wings contain biological fluorophores that cause them to fluoresce under UV light. This allows certain bugs to be seen more easily and attracted to black light bug zappers.
Bugs Attracted to Black Lights
Here are some of the main insects drawn to black light:
Moths
Moths rely on moonlight during their nighttime activities. The moon reflects UV rays from the sun, helping moths navigate and hunt for food. As black lights mimic moonlight with UV wavelengths, they attract a variety of moth species.
Beetles
Many beetles are also attracted to UV light, particularly scarab beetles. The iridescent shells and wings of scarab beetles contain fluorophores that cause them to glow under black lights. This may attract other scarabs during mating rituals.
Scorpions
Scorpions glow brightly under UV light thanks to fluorophores in their exoskeletons. UV light helps scorpions detect prey and find mates. Black light scorpion hunts are popular because black lights make the creatures clearly visible.
Cockroaches
Cockroaches have UV-sensitive photoreceptors that help them navigate dark environments. Roaches are drawn to black lights set out on sticky traps and bug zappers.
Flies & Mosquitoes
Many flies and mosquitoes mistake the UV light for sunlight or moonlight and get lured into bug zappers. Yet not all fly species respond to black lights.
Spiders
Some spiders contain fluorophores that cause them to glow under black lights. Their webs may also fluoresce. Many indoor spiders are attracted to black lights as a food source, allowing people to locate and remove their webs.
Centipedes
Centipedes’ compound eyes perceive UV light. Black lights help centipedes hunt prey at night.
Silverfish
Silverfish are attracted to humidity and warmth. As black lights emit heat, they can draw silverfish out of hiding. The UV fluorescence of silverfish under a black light makes them easier to spot and eliminate.
Bugs Repelled by Black Lights
While black lights attract and reveal many undesirable pests, they repel or have no effect on other insects:
Bees
Bees cannot see into the UV spectrum. Their eyes contain photoreceptors for visible blues and greens, not ultraviolet hues. Black lights have no influence on bee vision or behavior.
Ladybugs
Scientists have found no evidence that ladybugs are either attracted to or repelled by black lights. As important natural predators, ladybugs are unlikely to be lured into bug zappers.
Butterflies
Butterflies rely on red, orange, and yellow flower colors for navigation, not UV wavelengths. Black lights do not attract butterflies.
Fireflies
Fireflies produce their own bioluminescent light through a chemical reaction. They do not use external light sources like UV for navigation. Black lights should not attract fireflies away from their mating grounds.
Lightning Bugs
Similarly, lightning bugs (firefly larvae) glow via bioluminescence. Black lights do not draw these beneficial beetles away from their habitats.
Chiggers
Trombiculid mites, also called harvest mites or chiggers, are parasitic pests known to avoid light. Black lights help repel chiggers.
Fleas
Cat and dog fleas dislike bright lights, making them less likely to inhabit areas illuminated with black lights. Black lights can disrupt flea infestations.
Springtails
Primitive hexapods called springtails are photophobic, meaning they avoid light. The UV rays from black lights help deter springtails.
Earwigs
Earwigs are nocturnal insects that hide from light. They are repelled by illumination from black lights.
So while black lights attract moths, beetles, cockroaches, and other unwanted pests, they repel or do not affect beneficial insects like bees. Consider the types of insects you want to eliminate before deploying black lights as a bug control method.
Do Bugs Avoid Black Lights?
Certain insects clearly avoid black lights, including:
– Fleas
– Chiggers
– Springtails
– Earwigs
These bugs have an aversion to illumination, especially the UV wavelengths from black lights. They tend to inhabit dark, secluded spaces away from light sources.
Other household pests like bed bugs and ants do not have a strong reaction to black lights. There is little evidence that black lights alone effectively repel these insects.
Here is a table summarizing how different bugs respond to black lights:
| Bugs Attracted to Black Lights | Bugs Not Affected by Black Lights | Bugs Repelled by Black Lights |
|---|---|---|
| Moths | Bees | Fleas |
| Beetles | Butterflies | Chiggers |
| Scorpions | Ladybugs | Springtails |
| Cockroaches | Fireflies | Earwigs |
| Flies | Lightning Bugs | |
| Mosquitoes | ||
| Spiders | ||
| Centipedes | ||
| Silverfish |
This table shows how black lights attract moths, beetles, and other unwanted pests but repel fleas, chiggers, springtails, earwigs, and other photophobic insects.
Should I Use a Black Light Bug Zapper?
Black light insect traps and zappers take advantage of UV lighting to attract and kill flying insects like moths, mosquitoes, and beetles.
Here are some pros and cons of using a black light bug zapper:
Pros:
– Effective at trapping some nuisance insects attracted to UV light, including moths, beetles, mosquitoes, and flies
– Provides satisfying zapping sound when insects are electrocuted
– Useful for outdoor spaces like patios and porches
– Models with adhesive boards trap insects without mess
Cons:
– Electric zappers can singe insect fragments that collect on bulbs
– Not effective against insects repelled by or indifferent to black lights
– Traps beneficial predators like ladybugs and lightning bugs
– Adhesive can become covered with dead insects
– Bulbs require replacement overtime
– Only traps insects directly around device
If you want to eliminate occasional flying pests on a patio, a UV bug zapper can be helpful. But for whole-home pest control or eliminating UV-averse insects, use other methods like sanitation, traps, and targeted sprays. Avoid using black lights near gardens that attract beneficial insects.
Should I Use Black Lights for Spider Control?
Black light spider traps take advantage of certain spiders’ attraction to UV light wavelengths. The black lights lure spiders out of hiding spots and onto adhesive boards.
Here are some advantages and drawbacks of using black lights to control spiders:
Pros:
– Makes spider webs glow brightly to easily locate them
– Traps spiders without insecticides
– Can eliminate spiders in hard-to-reach places
– Versatile for use indoors and outdoors
Cons:
– May attract additional spiders from outside
– Not effective against all species
– Can trap beneficial spiders like wolf spiders
– Bulbs require occasional replacement
– Only traps spiders directly around device
– Requires regular adhesive sheet changes
For managing common nuisance web spiders in discrete areas indoors, black light traps can be useful. But they likely won’t fully eliminate infestations or discourage spiders from returning. Combine traps with vacuuming and sealing cracks to reduce spider access. Avoid outdoor use near beneficial garden spiders.
Conclusion
Certain flying insects like moths and mosquitoes are attracted to the UV light emitted by black lights. This allows black light traps and zappers to effectively eliminate some occasional pesky bugs in discrete outdoor areas.
However, many crawling insects and spiders common in households do not react strongly to black lights alone. Photophobic pests like fleas, chiggers, springtails, and earwigs avoid black lights.
Consider pest species and populations before deploying black light insect traps. Targeted sanitation, sealing, and pesticide methods often provide better whole-home control. But black lights can be a useful supplement for trapping UV-drawn bugs in specific zones. Monitor traps regularly and use caution around gardens that attract beneficial insects.