Bed Bugs in the Mattress: How to Detect and Get Rid of Them?

Bed bugs are among the most feared pests in a home. Silent, nocturnal, and remarkably resilient, they readily settle in the seams of a mattress, at the heart of the box spring, or along the bed slats — exactly where you spend seven to nine hours each night. Their presence has nothing to do with a lack of cleanliness: anyone can find their home infested, and bed bugs can be transported from one place to another when moving an object in which they reside — bedding, suitcase, bag, clothing. This guide explains step by step how to identify them, treat your bedding, and avoid a recurrence.

What is a bed bug?

The bed bug (Cimex lectularius) is a blood-sucking parasitic insect — it feeds exclusively on human blood. As an adult, it measures about 4 to 7 mm, is reddish-brown in color, and has a flattened body that allows it to slip into the smallest cracks. These insects cannot fly and only move by walking a distance of a few meters.

Bed bugs are attracted by vibrations, heat, odors, and carbon dioxide (CO₂) emitted by individuals — which explains why the mattress is their preferred refuge. They never live on humans themselves; they only approach to feed at night and then return to their hiding place.

Signs of an infestation: how to know if you have one?

Detecting an infestation early is crucial. The sooner it is addressed, the more effective the treatments are. Several clues can suggest their presence.

Characteristic bites on the skin

The bumps related to bed bug bites are often red and flat, except in cases of allergic reactions where they swell. They usually appear in lines or small groups on areas of skin exposed during sleep: arms, shoulders, neck, legs. One of the most well-known characteristics is the “breakfast, lunch, and dinner” pattern: several bites aligned along the same contact area with the sheet or pillow.

Often, at the beginning of the infestation, the bugs bite only one person in the household, which can skew the diagnosis: the other occupant of the bed shows no marks, and the infestation is underestimated or wrongly attributed to other causes (allergies, mosquitoes, dust mites).

Marks on bedding and surfaces

Examine your bedding — mattress, sheets, pillows — for signs of activity: carefully check the seams and folds of the mattress, favored hiding spots for these pests. Specifically, you may observe:

• Small dark brown or black spots on the seams and fabric: these are bed bug droppings, composed of digested blood. They resemble fine marker stains and permanently stain light fabrics.
• Moults (exuviae) that are translucent and yellowish: bed bugs molt five times before reaching adulthood, leaving behind empty skins.
• Whitish and tiny eggs (about 1 mm), often laid in clusters in corners.
• Live or dead insects, especially visible if you flip the mattress and inspect the seams in bright light.

A sweet and musty odor

An advanced infestation emits a characteristic odor, often described as sweet and slightly musty. If you enter a room and perceive an unusual scent reminiscent of coriander or a sweet fermentation, this may be an additional warning signal.

Sleep disturbances

Infestation by bed bugs alters sleep quality (insomnia) and has psychological and relational repercussions. Some people describe increasing anxiety about going to bed, unexplained nighttime awakenings, or chronic fatigue. These symptoms should prompt a thorough inspection of the bedding.

How to inspect your mattress and room

A thorough inspection is the first step before any treatment. Equip yourself with a powerful flashlight and a pocket mirror to reach hard-to-access areas.

1. Remove all sheets and covers and place them directly in a sealed plastic bag for washing.
2. Flip the mattress and examine every seam, every flap, every tufted area, paying particular attention to the corners.
3. Inspect the box spring: slats, wooden supports, bed legs, and spaces between the boards are common hiding spots.
4. Expand the inspection to the entire room: continue by scrutinizing surrounding furniture, paying particular attention to crevices and cracks, without neglecting baseboards and electrical outlets, where these insects can also slip in skillfully.

Treatments to eliminate bed bugs

Once the infestation is confirmed, it is essential to act methodically and simultaneously on the entire environment — not just the mattress. A rigorous cleaning, including vacuuming, washing at high temperatures, and heat treatment, is essential.

1. Deep vacuuming

Thoroughly vacuum the entire mattress, box spring, and bed frame. Pay special attention to seams, folds, and corners. Vacuuming a mattress is the best way to capture bed bug eggs and adult insects. Immediately empty the vacuum bag or canister into a tightly sealed plastic bag, taken out of the home.

2. Washing at high temperatures

All bedding — sheets, duvet covers, pillowcases, mattress protectors — must be washed at a minimum of 60 °C, a lethal temperature for bed bugs at all stages of development. If some textiles cannot withstand this temperature, put them in the dryer on maximum power for at least 30 minutes. Store the treated laundry in airtight plastic bags until the home is declared safe.

3. Heat treatment (dry steam)

Heat is one of the most effective treatments against bed bugs. A professional steam cleaner delivering a surface temperature above 120 °C destroys insects and their eggs on direct contact. Slowly pass the nozzle over all surfaces of the mattress, focusing on the seams. Caution: a simple household steam cleaner with low pressure may lack power — check the actual temperature delivered at the treatment surface.

4. Insecticides and treatment products

Several insecticides are authorized for domestic use against bed bugs in France. Formulations based on synthetic pyrethroids or diatomaceous earth (diatomaceous powder) are the most common. Diatomaceous earth acts mechanically — it damages the insects’ cuticle — and does not develop resistance. It should be applied in a thin layer in corners, cracks, and under the bed frame, and left in place for several days.

Caution: bed bugs have developed resistance to certain families of insecticides in many regions of the world. A single product is generally not enough to eradicate an infestation: it must be combined with other mechanical and thermal methods.

5. Consulting a professional

A professional exterminator is your best bet for eliminating bed bugs in the case of an established infestation. Specialized companies have powerful heat treatment equipment (heating an entire room to over 50 °C for several hours) and can use professional biocides that are more effective than consumer products. In France, these interventions typically cost between a few hundred and a thousand euros depending on the treated area and the chosen protocol — request multiple quotes.

Should I throw away my mattress?

This is often the first reaction, but it is not always necessary or sufficient. A new mattress can be infested within a few days if the room and furniture have not been thoroughly treated. However, if the mattress is old, very worn, or if the seams are irreparable, replacement may be considered — taking care to place it in a sealed cover before removing it from the home to avoid contaminating common areas.

If you keep your mattress, investing in a full bed bug-proof cover (called “encasement”) is highly recommended after treatment. These covers completely encase the mattress, including the seams, trapping any potential survivors who will starve to death in a few months, and preventing any new colonization. They also serve as an excellent monitoring tool: being smooth and clear, signs of bed bugs are immediately visible.

Preventing reinfestation

To avoid a new infestation, the entire environment must be treated: bedding, box spring, and room included. A few habits can help reduce the long-term risk:

• When traveling, avoid placing your luggage on the bed or directly on the floor of the hotel room. Quickly inspect the mattress and headboard upon arrival.
• When purchasing second-hand furniture (mattress, bed frame, sofa, chair), carefully inspect the seams and corners before bringing the furniture into your home.
• If you live in an apartment building, be vigilant during moves within the building or if neighbors have reported an infestation: bed bugs travel through electrical outlets, baseboards, and common conduits.
• Place traps under the bed legs: smooth plastic devices prevent bed bugs from climbing up the legs, and allow for monitoring of any movements.

To find all the maintenance tips for your bedding and extend the lifespan of your mattress, check out our dedicated section: Maintaining your bedding — all our tips .

Frequently asked questions about bed bugs