Bed bugs are small, flattened insects with piercing mouth parts, who feed on the blood of warm-blooded animals (including humans). They are wingless and reach about the size of a ladybug when they are full grown.
They also give off a sickening stench that can become quite overpowering and disgusting when an infestation is severe. Many have tried to tell bed bugs, in the kindest possible manner, about their body odor problem; but alas, it's been to no avail. They don't take the hint.
Bed bugs reproduce prolifically. It's not at all unusual for exterminators to encounter thousands of bed bugs in a single mattress. They also can spread to adjacent bedrooms (or adjacent units in apartment houses, hotels, motels, condos, co-ops, and other multiple dwellings), so one infested room or unit can rapidly lead to a bed bug problem spreading to an entire building.
Because of this threat, some landlords are requiring new tenants to have an exterminator inspect or treat their belonging before they move in. Tenants, on the other hand, often hire exterminators to inspect apartments before they move into them. If bed bugs are found, they either require the landlord to treat the apartment, or they look for some other place to live.
Some exterminating companies even have specially-equipped trucks or trailers that they use to treat people's household belongings on-site. They roll up to the house, carry all the customer's stuff into the truck, and treat it right there using either heat, cold, or fumigants. It's becoming quite a big business.
Unlike some other parasites, bed bugs don't actually live on a person's body. They live near where the person sleeps, usually in the bed. But they can also live pretty much anywhere in or near the room where the person sleeps; and as their numbers increase, they will even spread to adjacent rooms in all directions.
Because of their tiny size, they can live in cracks and crevices about the size of the thickness of a human fingernail. They're often found behind switch plates, in picture frames, under the edges of carpets, and, of course, in beds, box springs, mattresses, and other furnishings.
Adult female bed bugs lay two to four eggs a day in crevices in upholstery, furnishings, baseboards or other trim, picture frames, or pretty much anywhere else they can find a suitable crack, crevice, or void in close proximity to humans. Bed bugs won't be winning any Mother of the Year awards, however. This act of laying her eggs where her young will have an easy time finding a meal is the last act of kindness a bed bug mother will show to her young. Once the young bed bugs hatch, they'll be on their own from day one.
The nymphs hatch about one to three weeks after the eggs are laid, and immediately set out looking for a blood meal. The nymphs undergo five molts before reaching adulthood, and the total time from egg to adult ranges from one to two months. They must consume at least one blood meal before each molt, and adult females must consume at least one blood meal before laying eggs.
Bed bugs feed at night, so they tend to take up residence in close proximity to where their hosts sleep. It makes life easy for them. Why commute if you don't have to? Better to work at home.
Adult bed bugs usually live in structural cracks and gaps in bed frames, night tables, and headboards; as well as in mattresses and structural elements of a room. But they also may hide in the room's baseboards and other trim, in furniture, and even inside wall and ceiling voids.
Wherever they choose to hide, however, it is there that they will patiently lie in wait until you hit the sack and fall asleep.
And then they make their move.
Attracted by the warmth of a sleeping human body and the carbon dioxide that we exhale, bed bugs climb, crawl, or fall onto their hosts and start feeding, quietly sucking blood until they are full. Once they are full, they depart without so much as a burp, much less a "thank you," and return to their hiding spaces.
Unlike the case with many other pest problems, obsessive cleanliness is no guarantee that you won't have a bed bug problem. You don't have to be a slob to have a bed bug problem. But it helps.
The reason for this is that even though bed bugs don't really care whether your home is clean or dirty, frequent vacuuming and cleaning will reduce the chances of a few stray, hitchhiking bed bugs becoming established in your home. So if you happen to carry a bed bug or two home with you on the subway, their chances of becoming established in your home are less favorable if they're sucked into a Hoover before they find a place to live.
That being said, bed bugs can infest even the most immaculate of homes; so keeping a clean home reduces your bed bug risk slightly, but it's not a guarantee.
Bed bugs, like most creatures that suck human blood for a living, are pretty gross. They can even gross out exterminators -- and believe me, that's not easy to do.
One old friend of mine who recently retired from the pest control profession tells a story of a bed bug job so bad that he stripped naked outside his home before going in, for fear of carrying hitchhiking bed bugs into his home. Seeing as how he lives in New York City, no one paid any attention. But I digress. The point is that even exterminators are grossed out by bed bugs.
In terms of actual health risk of bed bugs, however, the jury's still out. Bed bug bites affect people differently. Some people get terrible rashes and welts that are accompanied by intense itching and even pain, but others seem to have little or no reaction.
In terms of actual disease transmission, bed bugs are believed to be theoretically capable of transmitting relapsing fever, Chagas disease, and possibly hepatitis. They also are believed to be capable, in theory, of transmitting MRSA (Methicillin-resistant Staphylococcus aureus) and some other serious diseases, but there's little evidence that this actually happens. The results of studies into actual disease transmission by bed bugs have been inconsistent, with almost all studies failing to find any evidence of disease transmission.
Still, the bites are annoying enough and can lead to infection. Some people are also particularly sensitive to bed bug bites and can suffer serious, painful inflammation and other skin conditions that can require medical treatment. Or as the CDC so clearly and succinctly puts it:
"Bed bug bites can result in clinical manifestations; the most common are small clusters of extremely pruritic, erythematous papules or wheals that represent repeated feedings by a single bed bug... Less common but more severe manifestations include grouped vesicles, giant urticaria, and hemorrhagic bullous eruptions ... Bites should be managed symptomatically with topical emollients, topical corticosteroids, oral antihistamines, or some combination of these treatments....
Although bed bugs could theoretically act as a disease vector, as is the case with body lice, which transmit Bartonella quintana (the causal agent of trench fever) among homeless persons..., bed bugs have never been shown to transmit disease in vivo..."
So in a nutshell, some people can get serious rashes from bed bug bites, and the bites can become infected. Other people will have almost no reaction at all. There is also evidence that they are capable of spreading several serious disease, but no clear-cut evidence that they actually do.