How to Know if You Have Bed Bugs: 7 Early Signs to Look For

7 early signs of bed bugs in your home or apartment and how to know if you have bed bugs

Worried about bed bugs in your home?

Bed bugs are notoriously hard to find and even harder to get rid of, especially if you live in densely populated places like New York City. But despite their sneakiness, it isn’t impossible for a vigilant homeowner or apartment renter to recognize the early signs of a bed bug infestation.

One of the best ways to protect yourself and your family from these tiny, blood-sucking pests is to find and exterminate them early on—before they can reproduce and spread.

In this article we’ll explain the 7 early signs of bed bugs, as well as where bed bugs hide and how to perform a simple visual inspection of your home.

7 Early Signs of Bed Bugs

If you suspect that bed bugs have invaded your home, it’s well worth your time to understand and familiarize yourself with these early warning signs:

  1. Musty odors
  2. Bed bug bites
  3. Bloodstains on sheets
  4. Fecal marks
  5. Shell casings
  6. Bed bug eggs
  7. Live bed bugs

These signs are in order based on how much certainty each warning sign can provide when it comes to confirming the presence of bed bugs, starting from the least reliable sign (odors) to the most reliable (live bed bugs).

In general, these signs of bed bugs may require professional confirmation to be certain of bed bugs, but this article will give you an idea of when to consider seeking help.

1. Odors

  • An unusual, musty odor with no apparent cause
  • Bed bug pheromones are often compared to the scent of raspberries, coriander, cilantro, or almonds
  • A severe bed bug infestation may smell like rust, wet towels, and moldy laundry
Signs of bed bugs include odors that can smell like cilantro, raspberries, rust, and moldy laundry

Sometimes, the first hint that something is amiss comes from our sense of smell. If you notice an unusual, musty odor in your bedroom that doesn’t seem to originate from an obvious source (like a pile of dirty laundry) it might be an early sign of bed bugs.

Bed bugs emit “alarm” pheromones in response to being bothered or threatened. These pheromones produce certain odors that may smell slightly sweet or musty. People who have experienced it firsthand describe the smell as somewhat similar to raspberries, coriander, cilantro, or almonds.

Normally, the smell of pheromones is very faint—practically imperceptible to the human nose. Unless you’re a trained bed bug-sniffing canine, your chances of noticing the raspberry-like pheromone smell from bed bugs are very low.

When you have a large number of bed bugs living together, the smell of their pheromones gets mixed together with the odor of dead bed bugs, shed shell casings, and bed bug excrement. The result is an unpleasant, rusty smell that gets worse as the infestation grows more severe.

Compared to other early signs of bed bugs, odor is typically the least reliable. That’s simply because when there are only a few bed bugs around, their odor is too faint for humans to notice. Furthermore, most people aren’t familiar with the scent of bed bugs, so even if you sense something, you’re likely to mistake the smell for something else.

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2. Bites

  • Small, red, itchy bumps
  • Most common places for bites include arms, hands, and legs
  • Sometimes appears as clusters of 3 or 4 bites in a line (“breakfast, lunch, and dinner” pattern)
Signs of bed bugs include clusters of red itchy bumps that appear during the night

Waking up to find itchy red bumps can be an alarming first sign of bed bugs.

Bed bugs are ectoparasites that feed on our blood while we sleep. They tend bite areas of the body where bare skin that is exposed during the night, such as arms, hands, and legs.

However, bites alone are not enough to diagnose a bed bug problem. That’s because different people can react very differently to bed bug bites, so there’s no definitive way to distinguish them from other insect bites. In fact, a whopping 30% of people don’t exhibit any skin reactions at all to bed bug bites.

While everyone reacts differently, the most common symptom of bed bug bites is red, itchy bumps appearing in small clusters. Some people refer to this as the “breakfast, lunch, and dinner” pattern, which describes bed bug bites as appearing in small clusters or lines of 3 bites. But in reality, bed bug bites can also appear as single bites or in random patterns.

As a side note, bed bug bites are usually not dangerous and do not transmit any known diseases. However, some people may experience allergic reactions to certain chemicals in bed bugs’ saliva.

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3. Bloodstains

  • Unexplained red or rust-colored stains
  • May appear as small splotches or smears on bedsheets, clothing, and pillows
  • Check first for other probable causes
Signs of bed bugs include clusters of red itchy bumps that appear during the night

Even though we don’t notice bed bugs when they’re feeding on us, they don’t always get away unscathed.

After a bed bug becomes engorged with blood, its original flat, seed-like appearance becomes elongated and bloated, resembling a tiny football. If you suddenly move or shift your body in your sleep, you might inadvertently crush a bed bug that just finished feeding.

While it doesn’t usually kill them, it causes some of the blood they just fed on to leak out and create a noticeable red or rust-colored stain.

If you see something that appears to be a bloodstain on your sheets, clothes, or pillow, check your body first to see if you can find a cut or scab that might be the cause. If there’s no other explanation for the bloodstain, then it might have been left behind by an unlucky bed bug.

Sometimes, bloodstains might also come directly from bed bug bites. Bed bug saliva contains an anticoagulant that prevents blood from clotting while they feed. After they finish their meal, the bitten areas may continue to bleed for a short while.

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4. Fecal Marks

  • Tiny, dark brown or black spots about the size of a pen tip
  • Usually clustered around harborage areas, but can also be found on sheets and clothing.
  • Dark smears on fabric resembling magic marker stains after being washed
Signs of bed bugs include clusters of red itchy bumps that appear during the night

Compared to the bloodstains that we described above, bed bug fecal marks (also called “fecal spotting”) are much smaller and darker.

These small, dark spots resemble ink dots from the tip of a pen or marker. The average size is about 2–4 times larger than a period at the end of this sentence.

Fecal marks come from bed bug droppings, which consist of digested human blood. The digested blood appears dark brown or black in color and, because it contains iron, gives off a faint, rusty smell that contributes to the overall unpleasant odor of a bed bug infestation.

Bed bug fecal spotting can occur anywhere—on sheets, pajamas, mattresses, headboards, box springs, walls, curtains, and other types of surfaces. You can usually find them in large numbers around bed bug hiding places and harborage areas.

On fabric, bed bug fecal marks can be quite difficult to wash out. Water causes them to smear in a distinctive fashion, resembling magic marker stains.  

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5. Bed Bug Eggs

  • Pearly white, oval-shaped
  • 1 mm long; about the size of a pinhead
  • Loosely stuck to various types of surfaces
  • Usually found near bed bug harborage areas
Signs of bed bugs include clusters of red itchy bumps that appear during the night

Female bed bugs can lay between 1-7 eggs per day, which typically hatch within 7-10 days.

In terms of appearance, bed bug eggs are about 1 millimeter long, pearly white in color, and oval-shaped. They resemble tiny grains of rice that are about the size of a pinhead.

Eggs are visible to the naked eye, but they can be difficult to recognize unless you know what you’re looking for. At the end of each egg is a hinged cap, which is where the newly hatched beg bug emerges from. Bed bug eggs that are more than 5 days old have a darkened eye spot; however, this can only be seen under a microscope.

Here are some pictures of what bed bug eggs look like:

Hatched bed bug eggs on the fabric of a box spring. (Source: Gary Alpert, Harvard University,
Hatched bed bug eggs on the fabric of a box spring. (Source: Gary Alpert, Harvard University)
Bed bug eggs in a crevice between cushions. (Source: Ben Hottel, University of Illinois)
Bed bug eggs in a crevice between cushions. (Source: Ben Hottel, University of Illinois)
Bed bug eggs in upholstered furniture. (Source: Ohio State University)
Bed bug eggs in upholstered furniture. (Source: Ohio State University)

When depositing their eggs, they use a glue-like material to adhere them to surfaces. As a result, you’ll most likely find these tiny, white eggs loosely stuck to crevices between fabrics or wooden surfaces.

Similar to fecal spotting, eggs are commonly found around harborage areas. However, female bed bugs tend to wander around when they’re pregnant, potentially spreading the infestation to other areas as well as neighboring apartments.

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6. Shell Casings

  • Yellowish-brown, translucent exoskeletons shed by juvenile bed bugs
  • Comes in various sizes throughout the bed bug’s molting cycle
  • Reliable indicators of a bed bug infestation
Signs of bed bugs include clusters of red itchy bumps that appear during the night

Bed bug shell casings (sometimes called shed skins or husks) are a reliable early sign of a growing infestation.

Shell casings are the translucent, hollow husks of juvenile bed bugs, and they’re often easier to find than the bed bugs themselves. They can be found anywhere that bed bugs hatch and breed—check mattress seams, upholstered furniture, and in holes, cracks, and crevices within wooden furniture.

As bed bugs go through 5 lifecycle stages before reaching adulthood, they’ll shed their exoskeleton several times.

The result of this process is what we call “shell casings” or “shed skins” in various sizes. Sometimes this makes identifying shell casings a bit tricky because most people aren’t familiar with the sizes and shapes of bed bug nymphs.

However, if you already suspect bed bugs and you discover yellowish, translucent shells in common bed bug hiding places, then you should consider contacting your local pest control professional for an inspection.

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7. Live Bed Bugs

  • Small, flat, reddish-brown insects around the size of a flaxseed
  • Often found congregating in tight cracks and crevices
  • Sometimes confused with baby cockroaches, carpet beetles, spider beetles, and other small insects
Live adult bed bug found and captured by MMPC inspector

Finally, the most obvious sign: finding live bed bugs in your home.

Bed bugs are flat, oval-shaped insects that are reddish-brown with a large abdomen, short antennae, and 6 legs.

They’re about the size of a flaxseed or a small apple seed. Adult bed bugs typically measure between 1/6–1/4 inch long (4–7 mm), while nymphs are can be as small as 1/16 inch long (1 mm).

Normally, bed bugs don’t like to wander around unless they need to feed. During the day, they typically find a hiding place and stick to it. For this reason, many people never see live bed bugs until the infestation becomes severe. Only when their hiding places are disturbed, like when you’re packing for a move, will bed bugs be discovered.

People also get bed bugs mixed up with other household insects. In our experience, the most common bugs that people mistake for bed bugs are baby cockroaches, carpet beetles, and spider beetles.

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Where Do Bed Bugs Hide?

With their tiny, flat bodies, bed bugs can squeeze themselves into just about any crack or crevice that’s bigger than 2 millimeters.

They tend to hide in the seams of mattresses, in the joints of furniture, inside cracks and crevices within walls and baseboards, and even inside electrical outlets or along the folds of curtains. These are all areas that you’ll want to thoroughly check for the early signs of bed bugs mentioned above.

From our experience as professional bed bug exterminators in NYC, here are some very common examples of bed bug harborage areas:

  • Bed – pillows, bedsheets, mattress seams, headboards, bed frames, and box springs
  • Next to Bed – nightstands, dressers, rugs, and storage boxes
  • Furniture – couches and cushions, bookshelves, tables, desks, chairs, rugs, and pet beds
  • Walls – wallpaper, baseboards, window and door frames, curtains, pictures and posters, electrical outlets, and smoke alarms
Pillow cases
Bed frames
Mattress seams

How to Perform a Visual Inspection for Bed Bugs

To perform a simple visual inspection for bed bugs at home, you’ll need a flashlight and a thin, rigid card (e.g. business card, playing card, or old credit card).

  1. Examine pillows and bed sheets for fecal marks and bloodstains.
  2. Remove bed sheets and check around the edges and seams of your mattress for bed bugs, shell casings, and eggs.
  3. Remove the mattress and use your flashlight to search the crevices, corners, nooks, and crannies around your bedframe and headboard.
  4. For any cracks that are too small to see into, slide your card inside and use the thin, rigid edge to extract any bed bugs or debris hidden inside.
  5. Do the same thing to inspect nearby dressers, nightstands, and other wooden furniture. Pay attention to screw holes, which is another common hiding spot for bed bugs.
  6. Pull furniture away from the walls to check the backs and baseboards.
  7. Inspect couches and upholstered furniture by removing cushion covers and using your card to get into gaps and crevices.

Tips for Identifying Bed Bugs

If you found a bug in your home and you’re not sure if it’s a bed bug or not, read our article about identifying them here: What Do Bed Bugs Look Like & How to Identify Them.

Adult bed bug
Bed bug nymph

Here are some additional tips for recognizing and identifying bed bugs:

  • Bed bugs have a narrow head and thorax with a flat, oval-shaped abdomen.
  • Adults are brown or reddish-brown, while nymphs are pale and translucent.
  • They have 2 beady, black eyes that protrude out from the sides of their heads.
  • They have 6 legs and 2 antennae. Their antennae have 4 segments and stick out from the front of their heads.
  • Bed bugs have small, vestigial wing pads but they can’t fly. If it flies, it’s definitely not a bed bug.
  • Bed bug interceptors are a great tool to help catch and monitor bed bugs.

Still Not Sure if You Have Bed Bugs?

MMPC offers a free Pest Identification Service, so you can simply send a picture of any of the above signs and we will get back to you within a business day to help you confirm if you may have bed bugs. We are also happy to answer any of your questions (free of charge) and provide recommendations for next steps.

Bed bugs are a heavy burden to bear, and getting rid of them is a team effort. Hopefully, you now have a better idea of when to call in that team.

For more articles and information about bed bugs, please see our resource page and pest blog.

Bed Bug Resources: