Bed bug poop — also called bed bug fecal spots — is one of the earliest and most reliable signs of an infestation. If you know what to look for, you can catch a bed bug problem weeks before you start seeing bites or the bugs themselves.

What Does Bed Bug Poop Look Like?

Bed bug droppings are tiny, dark, and ink-like. Each spot looks like a small dot made with a felt-tip pen:

• Color: Dark brown to black (it's digested blood)
• Size: About the size of the tip of a ballpoint pen — roughly 1 mm
• Texture: Smooth on hard surfaces, slightly raised; absorbs into fabric and spreads outward
• Pattern: Often appears in small clusters of 5–20 spots rather than scattered individually

Where to Look for Bed Bug Fecal Spots

Bed bugs poop where they hide and where they feed. Check these spots with a flashlight:

• Mattress seams and piping — especially along the top edge where the bugs feed on you
• Box spring corners and underside — lift the box spring and inspect every seam
• Headboard joints — wooden headboards are a favorite hiding spot
• Behind baseboards — particularly near the bed
• Sheet and pillowcase creases — rust spots on bedding are often where a bug was crushed
• Inside electrical outlets and light switch plates near the bed
• Seams of upholstered furniture where you sit or sleep

How to Tell Bed Bug Poop From Other Stains

Bed Bug Poop vs. Mold

Mold is fuzzy, green or black, and spreads in a pattern. Bed bug poop is smooth, dark, and appears in tight clusters of dots.

Bed Bug Poop vs. Roach Droppings

Cockroach droppings are larger (2–3 mm), cylindrical, and have ridges. Bed bug fecal spots are round dots much smaller than cockroach poop.

Bed Bug Poop vs. Dirt

Dirt brushes away. Bed bug poop smears into fabric when wet and is harder to remove — it's actually digested blood, so it behaves like a blood stain.

The Wet Paper Test

If you find suspicious dark spots and aren't sure what they are, try this test: touch a damp white paper towel to the spots. Bed bug fecal matter will smear and leave a reddish-brown blood stain on the paper. Dirt and mold will not.

Other Signs of a Bed Bug Infestation

Fecal spots are just one clue. Look for these additional signs:

• Shed skins (exoskeletons) — pale, translucent casts in seams and cracks
• Live bed bugs — flat, reddish-brown, apple seed shape
• Eggs — tiny (1 mm), white, oval, glued to surfaces in clusters
• Bloodstains on sheets — small rust-colored smears where bugs were crushed
• A musty, sweet odor — heavy infestations release a scent often compared to raspberries or cilantro
• Itchy bites in lines of 3 on exposed skin after sleeping

What to Do If You Find Bed Bug Poop

1. Confirm with a photo. Upload a clear image of the spots and any bugs you find to our free bug identifier to be sure.
2. Contain the spread. Don't move belongings to other rooms — that's how infestations travel.
3. Wash and heat-treat bedding. Hot water wash, high-heat tumble dry for at least 30 minutes.
4. Vacuum thoroughly. Mattress seams, baseboards, and under the bed. Seal the vacuum bag and discard outside.
5. Get professional treatment. DIY usually fails for established infestations. Professional heat treatment has the highest success rate.

Can Bed Bugs Be Stopped Before an Infestation?

Yes. Regular inspection is the best defense. Check mattress seams and bedding every month, especially after travel. Use mattress encasements — they trap any bugs inside and make inspection easier. If you notice even a few fecal spots, act fast. Bed bugs multiply rapidly, and early detection is the difference between a quick fix and a costly extermination.