The main cause of bed bugs is human travel. Bed bugs don’t come from dirt, poor hygiene, or outdoor environments. They spread almost entirely by hitchhiking on luggage, clothing, furniture, and personal belongings as people move between locations. A single pregnant female hiding in a suitcase seam can start a full infestation within weeks.
How Bed Bugs Actually Spread
Bed bugs are obligate parasites, meaning they feed exclusively on blood and depend entirely on being near people. They can’t fly or jump, so they rely on crawling into items that humans carry from place to place. Luggage is the most common vehicle, but they also travel in used furniture, books, electronics, purses, and even the textured soles of sneakers. Any item with a seam, fold, or crevice can harbor a hiding bed bug.
This hitchhiking behavior is what makes bed bugs so difficult to prevent. You don’t “catch” them the way you catch fleas from a pet or pick up ticks in tall grass. You carry them in, usually without any idea it’s happening. A single night in an infested hotel room, a used couch from a curbside pickup, or a borrowed piece of luggage is enough to introduce them to your home.
Where You’re Most Likely to Pick Them Up
Pest professionals report finding bed bugs most frequently in single-family homes (91 percent of professionals have treated them there), apartments and condos (89 percent), and hotels and motels (68 percent). But the list goes much further: nursing homes (59 percent), schools and daycare centers (47 percent), offices (46 percent), college dorms (45 percent), hospitals (36 percent), and public transportation (19 percent). They’ve turned up in stuffed animals, wheelchairs, airplanes, school buses, and bedside lamps.
Hotels get the most attention, and nearly 80 percent of people say that’s where they’re most worried about encountering bed bugs. But apartments and homes are actually where infestations are most common, largely because bed bugs spread through shared walls, laundry facilities, and secondhand items in multi-unit housing.
Why They’re Drawn to You
Once bed bugs are inside your home, they find you by following biological signals your body produces. Carbon dioxide from your breath acts as a long-range beacon, activating their host-seeking behavior and drawing them directly from their hiding spots to your bed. Body heat reinforces the signal at closer range. They also respond to chemicals in human skin and sweat, including lactic acid.
Research on their behavior shows that hungry bed bugs exposed to human breath become visibly agitated and move almost directly toward the source rather than wandering randomly. This response is so targeted that researchers compare it to how other blood-feeding insects use carbon dioxide as a long-distance tracking cue before switching to heat and scent for the final approach. This is why bed bugs nest so close to where you sleep: they’re optimizing their access to these signals.
Why Infestations Have Gotten Worse
Bed bugs were nearly eliminated in developed countries by the mid-20th century, but they’ve come roaring back over the past two decades. Several factors explain the resurgence, but insecticide resistance is a major one. Bed bug populations have developed widespread resistance to pyrethroids, the most common class of insecticides used against them. With only a few approved chemical classes available for bed bug control, pest professionals have limited options when the standard treatments fail.
Combination products mixing pyrethroids with a second type of insecticide were developed as a workaround, but research published in Nature found that resistance to these combination products already exists in field populations. In lab tests, bed bugs exposed to these products over just a few generations became significantly harder to kill. The resistance developed quickly because it built on existing genetic variation in wild populations. In short, the chemicals that once kept bed bugs in check no longer work reliably, and the bugs are adapting faster than new solutions can be introduced.
Increased global travel has compounded the problem. More people flying more frequently means more opportunities for bed bugs to spread between cities and countries. The combination of resistant bugs and a highly mobile human population has created ideal conditions for infestations to multiply.
How to Spot an Infestation Early
Bed bugs leave physical evidence before most people ever see a live bug. The EPA recommends looking for rusty or reddish stains on sheets and mattresses where bugs have been crushed, dark spots about the size of a pen tip (fecal matter that often bleeds into fabric like ink), and tiny pale yellow skins shed by juvenile bugs as they grow. Eggs are roughly 1mm long, white to pale yellow, and typically clustered in mattress seams, headboard joints, and the edges of box springs.
Check these areas with a flashlight, paying close attention to piping along mattress edges, the underside of the headboard, and any cracks in the bed frame. Bed bugs are flat, oval, and about the size of an apple seed when fully grown, so they can wedge into surprisingly thin gaps.
Practical Steps to Avoid Bringing Them Home
When staying in a hotel, inspect the mattress and headboard before unpacking. Pull back the sheets and check the seams and corners of the mattress, the joints of the headboard, and the luggage rack itself. Keep your suitcase on the luggage rack rather than on the bed or floor, and keep it zipped when you’re not actively using it.
When you get home, unpack directly into the washing machine. Run everything through the dryer on high heat, because heat is what kills bed bugs. Washing alone typically won’t do it. Store your suitcase in a basement, garage, or closet rather than in or near your bedroom, and never slide it under the bed.
If you’re buying used furniture, inspect every seam, fold, and crevice before bringing it inside. Upholstered items like couches and mattresses carry the highest risk. Electronics, books, and picture frames picked up secondhand deserve a close look too. Bed bugs can survive an average of 70 days without feeding at room temperature, so an item that’s been sitting in storage or on a curb isn’t necessarily safe just because it looks clean.