Bed bugs

Bed bug bites: what they look like and how to confirm it is bed bugs

What a bed bug bite looks like

A bed bug bite is a red, swollen, itchy welt, from half a centimeter to two centimeters, without the small dark center of a flea bite. What gives it away is not the welt itself but the pattern and the timing. They appear in a straight line or zigzag, 3 to 5 in a row, because the bed bug walks a few millimeters between each bite while it looks for a blood vessel. They are on the parts of the body left uncovered while you sleep: face, neck, shoulders, arms, hands, and on the back or legs if you sleep without a blanket. And you notice them when you wake up, never after an afternoon in the yard.

One detail that confuses a lot of people: the reaction can be delayed. In some people the welt shows up a few hours later; in others it appears 1 to 3 days after the bite, and some people, about a third, don't react and nothing shows up. That is why it is common for one person in a couple to wake up covered in welts while the other has none, and for someone who traveled last week to start seeing them today, once back home.

Bed bug, flea or mosquito

• Bed bug: a line or zigzag of 3 to 5, on the face, neck, arms and back, when you wake up, every night. No pet is involved. If you change beds and the bites follow you, it is bed bugs.
• Flea: smaller dots with a dark center, on ankles and legs, at any time of day, in a home with a dog or cat or one you just rented. Full guide in flea bites.
• Mosquito: a single welt, pale in the center, on any exposed area, at dawn or dusk, and you heard the buzzing.

The bite alone doesn't give you certainty. To confirm, you have to look for the bed bug or its traces.

How to confirm it is bed bugs

Adult bed bugs measure 4 to 7 millimeters, are reddish brown, oval and flat like an apple seed, and hide during the day less than 2 meters from where you sleep. Check with a flashlight, at night or with the room dark:

• Mattress seams and piping, especially at the head of the bed and the corners. Lift the piping and look inside.
• Black dots the size of a pen tip, clustered, that smear if you rub them with a damp cloth. It is bed bug excrement and the most reliable sign.
• Small blood spots on the sheets, from bed bugs crushed when you move in your sleep.
• Translucent amber shed skins left by nymphs when they molt, and white one-millimeter eggs stuck in crevices.
• Box spring, bed frame, screws, legs and the joint between the headboard and the wall. Bed bugs prefer wood and fabric over metal.
• If the infestation is large, a sweetish smell similar to cilantro or overripe raspberries.

If you find one of these traces, you have your confirmation. If you find nothing but the bites continue, put double-sided tape on the bed legs and check after three nights. There is more detail on the inspection on the bed bug control page.

It is not about poor hygiene

Bed bugs don't eat dirt or crumbs: they feed on blood. A spotless house and a messy one are all the same to them. What they need is a sleeping person nearby and a crevice to hide in. They arrive in your suitcase after a hotel or hostel, in used furniture bought online, in a hand-me-down mattress, in clothes from a trip, or by walking between neighboring apartments through the ducts and electrical boxes of a condominium. In Costa Rica, the most common way in that we see is luggage.

To avoid bringing them home from a trip: at the hotel, check the mattress seam at the head of the bed before setting down your suitcase, leave it in the bathroom or on the metal luggage rack, and when you get back, unpack straight into the washing machine and dry on high heat. More in bed bugs in Costa Rica: hotels and travelers.

What to do about the bites

Wash with soap and water, apply cold for 10 minutes and, if the itching bothers you, take an over-the-counter antihistamine or use a 1% hydrocortisone cream. The welts go away on their own in one to two weeks. See a doctor if one becomes warm, has pus or a red streak, or if there are welts all over the body or facial swelling. It has not been shown that bed bugs transmit diseases; the problem is the itching, infection from scratching and the toll of not sleeping.

What NOT to do: the three things that scatter the infestation

Don't throw out the mattress. Bed bugs are not only in the mattress: they are in the frame, the baseboard, behind the headboard, in the nightstand. A new mattress gets infested within a week, and the old one, if you carry it down the hallway, spreads bed bugs throughout the house or the building. Besides, the mattress can be treated and encased.

Don't use spray or insecticide foggers. Supermarket spray doesn't kill them in their hiding places, but it does drive them away: bed bugs flee the treated room into the next room, the closet or the living room, and what was a one-room problem becomes a whole-house problem.

Don't switch rooms or go sleep on the couch. Bed bugs follow you: they detect heat and CO2, and within a few nights you have two infested rooms. While you wait for treatment, stay in the same bed, pulled away from the wall.

How to prepare the bedroom for treatment

• All bedding and the clothes in the closet go into sealed plastic bags, get washed and dried at high temperature (30 minutes in the dryer on high is what kills eggs and nymphs). Clean items go back into new bags and stay there until the treatment is finished.
• Clear the space under the bed and along the walls. Pick up whatever is on the floor.
• Don't move furniture to other rooms or take anything out of the bedroom without bagging it.
• Vacuum seams, the bed frame and baseboards the day before, and throw the vacuum bag out in a sealed bag outside.
• Leave access to the bed on all four sides and to the closet.

The general instructions are in how to prepare your home before and after fumigation.

How much it costs and when to call

Professional bed bug treatment is done per full bedroom: mattress, box spring, frame, headboard, nightstands, closet, baseboards, electrical boxes and crevices, with a residual product, and it includes a follow-up inspection at 15 days to confirm that no eggs were left to hatch. Price from ₡55,000 per bedroom, VAT included, with no travel fee in the GAM. You can go back in one hour after the application. If you have not fumigated in the last 6 months, it takes two applications and the second one is charged; the 30-day check only applies once the plan is complete.

Call as soon as you confirm the first trace. Every week that goes by, a female lays 5 to 7 eggs a day and the infestation spreads to another room. Date confirmed by WhatsApp in less than an hour, with service nationwide.

Frequently asked questions

How do I tell a bed bug bite from a mosquito bite?

A bed bug bite shows up when you wake up, in groups of 3 to 5 in a line or zigzag, and it repeats night after night on the same person. A mosquito bite is a single welt, you heard or saw the mosquito, and it also appears during the day or at dusk.

Why do they bite me and not my partner?

Both people get bitten. The difference is the reaction: about a third of people don't react to bed bug saliva and nothing shows up. That is why a shared bed can have only one person affected.

Do bed bugs transmit diseases?

It has not been shown that they transmit diseases to people. The harm is the itching, infection from scratching, lost sleep and anxiety, which is very real for those who suffer from them.

Can I get rid of bed bugs myself?

With only a few, caught early, it helps to wash and dry all the bedding at high temperature, vacuum the seams and encase the mattress. But bed bugs hide in frames, baseboards and electrical boxes that neither steam nor a vacuum can reach, and a half-done treatment scatters them. In practice it almost always ends in professional treatment.