Bed bug fecal matter on a wooden bed frame

What Do Bed Bug Droppings Look Like?

If you fear bed bugs and have done research you may know that they leave behind fecal matter, also known as bed bug droppings. Having a fear of bed bugs may have caused you to google them, nevertheless, one of the pieces of information you will often find is about the bed bug fecal matter. 

Bed bug droppings are one of the number one things I find as far as bed bug evidence goes when performing my bed bug inspection. We may discover bed bug fecal matter during our visual inspection for bed bugs. Moreover, finding fecal matter will confirm the presence of bed bugs. Sometimes a person will find a male vs female bed bug and they do not see any other signs of bugs. If you find one male bed bug, it is best to search your entire bed looking for bed bug fecal matter.

What Does Bed Bug Fecal Matter Look Like? 

It looks like black ink stains. If you find it on your mattress, bed frame, or box spring, you can take a wet Q-tip and try to smear it. If the dot smears, then it may be bed bug fecal matter. The next best thing you can do is keep searching the area for a live bug. 

How to Identify Bed Bug Droppings

  • Color – Is the color a dark blackish color? If not, then what you see is probably not bed bug fecal matter. This black poop is partially blood that they digest; it turns black when it is excreted. Often people will text me photos of light rusty colors that they find on their sheets. Bed bugs do not leave marks that are a light rusty color.
  • Size – About 1mm, give or take a little. Take a ballpoint pen or an ultra-fine point sharpie and make a dot. This is about the size of bed bug fecal matter.
  • Area – Bed bugs will usually leave their dropping close to where they are feeding. You will not find bed bug droppings across the apartment in the kitchen away from the bed unless you have many bed bugs roaming your place. Typically bed bugs eat, sleep, have sex, and poop all around the host. 
  • Shape – Fecal matter will be circular if it does not bleed into the fabric. If it seeps into cloth, then it will make the same crosshair type of lines on the side of where it is soaked in. The same way a Sharpie marker would look when you touch it to the fabric.
  • Consistency – Does your spot smear when you wipe it with a wet cloth or Q-tip? Moreover, bed bug droppings do not flake off. To clarify they are a liquid black poop. The bed bug droppings are NOT something you can pick up and collect into a bag.
  • Photos – Take some clear zoomed-in photos of your suspected fecal matter and email them to a bed bug specialist or entomologist in your area. 
  • Smear Test – Firstly, this test is good to let you know that the spot you saw is NOT from a bed bug. Additionally, just be aware that many other types of suspicious marks may smear as well, but they still may not be bed bug fecal matter. In short, if it doesn’t smudge, then it is probably not from a  bed bug. Another thing to keep in mind is that if the spot you are testing has soaked into a sheet or blanket, then you won’t be able to do this smear test on it. 

However, Other black spots that will smear can be from the following items: mascara, paint, pens, chocolate, certain types of mold, and various foods.

  • Bed Bug Blue Fecal Test Kit – Use a test kit like Bed Bug Blue to test your suspicious dots. When I am searching for bed bugs after the K9 alerts, I often use this test kit on suspicious black marks I find. I am glad that it exists because using it gives me factual accuracy.
  • Set some paper harborage monitor traps. If you take a plain white piece of paper and make it into fans you can place these around your mattress. – instructions are below under “what to do”-

Bed Bug Fecals Will Smear

Primarily bed bug fecal matter will be anywhere there are bed bugs. If the fecal matter is on a hard surface, it will smear. On the other hand, if it’s on a fabric surface, it won’t smudge because the liquid poop gets soaked into the fabric.

Smear Test For Bed Bug Fecal Matter

  • Take a Q tip or a rag, wet it. Make it damp but not soaked.
  • Next, take the wet Q-tip or rag and wipe the fecal matter.
  • If the spot smears and the Q tip or damp rag turns a brownish rust color, you may want to further investigate.

If the bed bug droppings are on a hard surface like the bed frame, we can test them with our kit called Bed Bug Blue. Likewise, this is a scientific test that confirms or denies the presence of bed bug fecal matter by turning a developing strip blue if you pick up bed bug fecal matter. 

Bed bug droppings are ink-like permanent stains. For example, look at some comparison photos below. Most importantly they do not go away over time and usually do not even wash out. When a sheet gets a bed bug stain on it, the stain does not wash out. To illustrate what will happen is that it gets lighter and fades with each washing, much the same way that a mark from ink would. For instance, it is hard to tell the difference between a magic marker stain and a bed bug stain on the fabric.

The signs of bed bugs are:

  • Bed bug droppings. Finding the droppings when you only have a few bugs can be quite a challenge. Often the fecal matter is located around the bed frame, mattress, box spring, or headboard. Consequently, when searching for it, pay special attention to any seams or creases. Sometimes I find it on the sheets and pillows too.
  • Live bed bugs. Keep in mind, that all bed bugs go through 5 stages after hatching. All bed bug sizes are visible with just the eyes.

Bed bugs, fecal matter, and shed skins on a blanket.
Fecal matter and bed bugs on fabric. You can see how the bed bug droppings seep into the fabric just like ink.

  • Shed skins. At first, these are rarer to find because they are harder to see; they are a light tan and tend to blend into things. Often when I arrive at someone’s apartment for an inspection, they are the most common thing people show me as possible proof. 98% of the time, the “shed skin” that they show me is not shed skin at all but often food debris, dust, or dirt. 

Bed Bugs are Attracted to Their Own Feces

The bed bug harborages are usually close to where the bed bug feces is. The bed bug fecal matter draws other bed bugs over to it as well. The University of Minnesota did a study in 2016 that determined that the bed bugs are attracted to 5 compounds (dimethyl disulfide, dimethyl trisulfide, (E)-2-hexenal, (E)-2-octenal, 2-hexanone) within their fecal matter, which is why you will often find them aggregating close to it.

Currently, researchers and scientists are working on chemical lure-type traps for bed bugs. The lure traps that are under development are using chemical compounds to attract the bed bugs, and so far, they are having great success.

What to do if You Find Something that Looks Like Bed Bug Fecal Matter?

  • You can get a bed bug mattress encasement (get one for the box spring too). The bed bug covers will help you monitor and turn your mattress and box spring into one seamless item. Monitoring will help you see if more spots turn up. 

  • Initially search your entire mattress, box spring, bed frame, and any fabrics near the bed. Visually searching is something you do slowly with a good flashlight. With this in mind, you’ll need to take each item off the bed and search all sides of it, paying particular attention to any wood seams or crevices. A bed bug can squeeze into the tiniest space.

Look at the photo below and take note of the wooden slats. Search each one of these on all sides with a flashlight. Then search the wall, brick walls have a lot of crevices if they are not sealed. In particular, search the entire wall and molding around the bed.

Bed frame with wooden slats and a brick wall.

  • If after searching you find nothing, set up paper monitors. These are simple to make and just require a white piece of paper. Fold the paper in a zig-zag-like way as if you are making a fan. Next, put 10-15 of the paper fans around your bed.  Place them under the mattress but allow them to stick out over the edge a tiny bit. 

There is no exact science as to where or how you place the paper fans. Below is one way you can put it, but yours may look differently depending on your particular bed. The point is that you are creating harborage and hiding areas within the creases of the paper. You would carefully open and check each fan for bugs, fecal matter, or shed skins weekly. 

Example of a paper monitor for bed bugs.
DIY paper monitor for bed bugs.
DIY paper monitor for bed bugs - placed on the side of a mattress.
Example of one place to put the monitor. You will put 10-15 of these around your bed.
  • Purchasing a steamer for bed bugs is not a bad idea. Steaming every crack and crevice around your bed can’t hurt, and if you are still concerned after following all of these steps, then hire a professional.

  • If you search your whole bed and do not find anything but are still concerned, you can hire a certified bed bug inspection company with a dog to search your home. We train our bed bug dogs to alert to live bed bugs or viable eggs. Most reputable K9 handlers will also perform a visual search after the dog alerts. 

What do bed bug droppings look like on a sheet?

Bed bug droppings on a white sheet

Bed bug feces on sheets look similar to a pen mark or magic marker dot. The bed bug feces on a sheet is dark blackish (if fresh) and greyish black/faded if washed. 

What does fecal matter from a bed bug look like on a bed frame?

Fecal matter from bed bugs on a wooden bed frame.

If the frame is a fabric, it may either bead up on the surface or soak in. If you see a dark circle, you can do a simple smear test. Take a wet q-tip and smear the dot. If it spreads in a line, you may want to inspect the area further. However, if the bed frame is wood, please look at our photos below.


What do bed bug droppings look like on wood?

Bed bug fecal matter on a wooden bed frame

On light-colored wood, the bed bug dropping will stain the surface of the wood, but you can still test it with the Bed Bug Blue Fecal Test Kit. First, do the simple smear test as described above. 

Bed Bug Feces on a Wall

Bed bug fecal matter on a wall and molding behind a bed.

If your wall has any cracks or crevices you might find bed bug evidence on the wall.

How to Identify Bed Bug Feces?

If the black stain you found did indeed smear, it is still not guaranteed from a bed bug. Although there is a kit called Bed Bug Blue; it lets you confirm scientifically that what you found is bed bug poop. The kit comes with Q tips, a proprietary solution, and a test paper.

Recently during an inspection, I found one single suspected fecal matter dot. More importantly, if I hadn’t had my Bed Bug Blue Test Kit with me then I wouldn’t have been sure it was a fecal mark. The test paper turned blue, so that confirmed my suspicion.

One bed bug dropping on a wooden bed frame.
This is the suspicious dot I found during a bed bug inspection.
Positive test result (blue line) from the Bed Bug Blue Fecal Test Kit.
Positive result from the Bed Bug Blue test kit.

FAQ on Bed Bug Droppings

Final Words on Bed Bug Fecal Matter

All in all, the best thing you can do if you found some suspicious-looking black dots that smear is not to panic. Firstly, start looking for a bug, or secondly hire a professional to look for you.