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

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Early Signs of Bed Bugs

Bed bugs (Cimex lectularius) are parasitic insects that feed on blood while we sleep. They have small, flat bodies enabling them to hide in tight gaps and crevices (as small as 2 millimeters) where they spend most of their time hiding.

Despite their sneakiness, it isn’t impossible for a vigilant homeowner or apartment renter to notice signs of a possible infestation. At MMPC, we perform thousands of inspections and other bed bug services each year. Based on our decades of experience, the best way to protect your family from these blood-sucking pests is to understand and recognize these 7 early signs:

People often start suspecting bed bugs after getting bites. They might discover bloodstains or fecal marks around the bed. Musty odors become noticeable over time, coming from an accumulation of blood, feces, and pheromones. Upon closer inspection, shell casings and eggs may be found in mattress seams and concealed hiding spots. Depending on the situation, seeing bed bugs may also be an important early sign.


bed bug bites close up

The usual symptoms of bed bug bites are small, red bumps on skin. They’re typically around 2–5 mm in diameter and accompanied by itching or swelling. Bed bugs like to feed on exposed skin during sleep, so common sites for bites are on the face, neck, arms, and legs.

Their bites often appear in clusters or zigzag lines. A characteristic pattern to look out for is bite marks in clusters of 3 or 4 located a few centimeters apart in a linear or zigzag arrangement. This is commonly referred to as the “breakfast, lunch, and dinner” sign.

It’s important to understand that everyone reacts differently to bed bug bites. In fact, approximately 30% of people don’t exhibit any visible signs of bites at all—no bumps, redness, or itching. Furthermore, the number and location of bites also depends on the level of the infestation. With only a few bed bugs present, bites may be isolated or infrequent. As their numbers increase, you might find bigger clusters on a nightly basis.

While getting bites is an important warning sign, they are not conclusive of a bed bug problem. We receive many emails from people concerned about bites which turn out to be from skin conditions or other pests like ticks and fleas.

Fortunately, 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.


You might discover bloodstains in your bed as a result of recent bed bug activity. Look for red or rust-colored stains that appear in small splotches or smears. The most common places to find them are on bedsheets, clothing, and pillowcases.

Where do the stains come from? Even though we don’t notice bed bugs while they’re feeding, they don’t always get away unscathed. When a bed bug is engorged, its abdomen swells with blood and almost doubles in size. If you suddenly move or shift your body, you might inadvertently crush it and cause blood to leak out.

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

But before jumping to conclusions, check your body first for other causes like cuts or scabs. If you can’t find another explanation for a bloodstain, then it might be from an unlucky bed bug.


fecal spotting on mattress

Fecal marks come from bed bug poop, which essentially consists of digested blood. Unlike normal bloodstains which are red or rust-colored, fecal marks look like dark brown or black spots (also referred to as “fecal spotting”).

Fresh droppings are very small (around 1–2 mm) and resemble ink dots from the tip of a ballpoint pen. They smear easily and give off a faint, rusty smell that contributes to the overall unpleasant odor of a bed bug infestation. Old droppings can soak into mattresses and fabrics over time, leaving behind stubborn stains that are difficult to wash out.

Bed bugs can leave fecal marks anywhere—on sheets, mattresses, headboards, box springs, walls, curtains, and other surfaces. However, they’re most often found in areas where bed bugs congregate, such as mattress seams and other harborage areas.


musty odors bed bug feces and debris

An unpleasant, musty odor in your bedroom (without an obvious source like mold) might indicate bed bugs, especially if you’ve also noticed bites or other signs. The smell is faint at the onset of an infestation and gradually worsens over the course of a few weeks.

Digested blood in bed bug feces contains iron, which oxidizes and produces a rusty smell. Also mixed in are unpleasant scents from dead bed bugs and shell casings left behind when they molt. This combination produces an overall musty odor frequently compared to rust, wet towels, and moldy laundry.

Bed bug pheromones also contribute to the odor, but not as much as most people believe. While it’s true that they smell slightly sweet and similar to raspberries or coriander, the scent of pheromones is extremely faint and often overpowered by the smell of feces and other debris.


bed bug shell casing

Juvenile bed bugs go through 5 instar stages before reaching adulthood. At each stage, they molt and leave behind hollow exoskeletons known as shell casings or shed skins.

These empty husks are usually pale, translucent, and yellowish-brown in color. They come in various sizes depending on the instar stage, ranging from 2–7 mm. Complete shell casings are shaped like bed bugs, but partial or fragmented pieces are harder to recognize.

Like fecal marks, shell casings are often found in mattress seams and other harborage areas where bed bugs breed and reproduce. They are important evidence of a growing infestation because they signal the development of new generations of bed bugs.


musty odors bed bug feces and debris

Bed bug eggs are pearly white and oval-shaped, resembling tiny grains of rice. They’re about the size of a pinhead and are barely visible to the naked eye, measuring only 1 mm in length.

At one end is a hinged cap, from which the newly hatched bed bug emerges. Eggs that are more than 5 days old have a darkened eye spot. However, this can only be seen under a microscope.

Unhatched eggs are soft to the touch, filled with fluid, and pop easily under a small amount of pressure, while hatched eggs may appear dry or wrinkled. Freshly laid eggs are covered in a sticky, glue-like liquid and loosely stuck to surfaces.

Female bed bugs lay between 5–20 eggs over the course of 10 days after a single blood meal.

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How to Check for Bed Bugs

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.

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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.

At MMPC, we

Being able to find and exterminate bed bugs early on—before they reproduce and spread—goes a long way

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 to look for.

7 Early Signs of Bed Bugs