Once introduced into a home, bedbugs can crawl into adjoining apartments or hitch a ride to another part of town in the cuff of a pant leg.

"Anyone who stays in a hotel, rich or poor, can bring them home in a suitcase," said Richard Kourbage, whose company, Kingsway Exterminating in Brooklyn, does about a dozen bedbug jobs a day. "Some of the best hotels in New York have them."

Unlike mice and roaches, which are abetted by filthy surroundings, bedbugs do just fine in a well-scrubbed home, although bedroom clutter gives them more places to hide and breed. When engorged with blood, they grow slightly plumper than the O on this page, although the nymphs, which appear almost translucent before their first meal, are not much bigger than the period at the end of this sentence.

And they don't dwell just in mattresses and box springs: any wall or floor crack the thickness of a playing card can accommodate a bedbug. Although some people try to treat the problem themselves, most hire exterminators, at $300 per room.

The modern bedbug is immune to hardware-store-variety insecticides, and setting off a cockroach bomb in the bedroom will only scatter them farther afield. And because they are active only at night, many people don't discover them until their population has grown into the hundreds, or even thousands.

Exterminators recommend bagging and washing every bit of clothing and fabric in the room and taking apart bureau drawers and bed frames in preparation for the application of four kinds of chemicals. The process often needs to be repeated.

Worst of all, bedbug sufferers say, is the stigma of living with an insect that feeds on blood -- though it does not transmit disease -- and leaves behind a trail of red bumps that many dermatologists mistakenly identify as hives or scabies.