Can You See Bed Bugs With a Black Light?

Can You See Bed Bugs With a Black Light

Yes, you can see bed bugs and their trail using a black light. The blood stains and fecal matter stains bed bugs leave on your mattress and bed sheets shine bright under a black light.

Many insects have phosphors on their shells that absorb ultraviolet light that makes them more visible.

How does a black light detect bed bugs?

Black light is a type of ultraviolet light, or UV light. UV light is similar to regular light in that they are both types of radiation. They are emitted by the sun and act in the same way, except that they are on different spectrums of light. The different light spectrums appear as different colors to the human eye. But because UV light has more energy and a higher wavelength, it is not visible to the naked eye. When you use a blacklight, it will look purple because that is the highest wavelength the human eye can see.

UV light reacts to phosphors, which is any substance that has luminescence. Luminescent substances absorb energy and release that same energy as light. Examples of things that have phosphors are some types of paints or inks, detergents, and human teeth and nails.

Are bed bugs drawn towards black light?

No, bed bugs do not like the light because they are photophobic. This means that they do not like the light and avoid it as much as they can. This is innate bed bug behavior that has helped the species survive for millenia. They realize that being exposed to light also exposes them to potential attacks, so it is exponentially better to stay in the dark.

So, shining a black light in the bed bug’s direction will make them hide out even more.

Will a bed bug glow under a black light?

Yes, bed bugs will glow under a black light. One of the theories that may explain this is that bed bug exoskeletons have a similar makeup as nails.

Other creatures that glow under a black light are spiders, grasshoppers, and scorpions. They become a luminous blue when exposed to a black light.

Can bed bugs see black light?

Most insects can detect black light, as well as green and blue. Judging from a bed bug’s behavior of fleeing when black light is shown on them, it is safe to say that they can, at least, detect black light.

Can I use a black light to detect bed bugs?

Yes, you can use a black light to detect bed light makes both the bed bug and their trail glow. Blood stains left by squished bed bugs, as well as their fecal matter stains also glow under a black light. Discarded bed bug shells also glow under a black light because the phosphors on a bed bug are mainly in its shell.

The downside of finding bed bugs using a black light is that the light may cause the bed bugs to panic and spread out to find new hiding spots. This will make targeting their harborages even trickier than it already is.

A better method for catching bed bugs for infestation detection is to set bed bug interceptor traps that you place in the feet of your bed. The bed bugs will climb into the trap but they will not be able to climb out. These are great for preventing infestations especially for bed bugs that come crawling towards the bed from the floor. This is a passive method for capturing bed bugs, so you just need to check periodically for bed bugs.

How do I search for bed bugs with a black light?

First, you need to remove all of the linen on your bed and to place all of it in a plastic bag. Seal the bag tightly with tape. If you do not have a plastic bag that is big enough, you can use an airtight plastic tub container. 

Your mattress and bed frame are the bed bugs’ favorite places to hide, so it should be the first place you check.

Flip your mattress and inspect the piping and edges of the mattress. Check the zipper as well, because that area has nooks and crannies that can easily hide bed bugs. If your mattress has folds as part of its textural design, check each one of them. Keep an eye out for anything that glows once you shine the black light on it.

Next, flip your bed frame so you can check all the joints, gaps, and holes with ease. These are prime spots for bed bug eggs.

Once you finish with your bed, move onto the furniture that are within six feet of your bed. Check also the walls and carpet around your bed as bed bugs may hide in there too.

Can black light kill bed bugs?

Yes, technically a black light can kill bed bugs. But it only works if the light is directly irradiated on the bed bug in close distance for over an hour. So, it will work, but it is not a practical method of bed bug extermination.

Any ultraviolet light damages both DNA and RNA, so excessive exposure to it can cause cancer. 

Can I use black light to kill bed bugs?

No, it is not reasonable nor practical to use black light to kill bed bugs. This is because bed bugs are afraid of UV light the same way they are afraid of regular light.

You would need to beam concentrated black light onto a single immobile bed bug for an hour to kill it. In your household, bed bugs are constantly moving especially if there is a light source beaming on them.

The bed bugs that are hidden will be unaffected by the black light.

You may be concentrating on the bedroom while there are bed bugs in the living room.


Yes, you can see bed bugs with a black light because their exoskeletons contain phosphors that become luminescent when hit by a black light. Black light can also detect the blood stains and fecal matter stains that bed bugs leave in their trail.

Even if it is possible to kill a bed bug using long exposure to black light, it is not a practical method of extermination.

Image: / Dmitry Bezrukov