Sleep tight, and don’t let the bedbugs bite. Until recently, the insects mentioned in that bedtime admonition conjured up images of straw-filled mattresses and less than sanitary conditions from the Middle Ages, the Wild West or a Third World country.

But bedbugs are making a comeback… possibly to a mattress near you.

The tiny bloodsucking parasites, which can be no bigger than the head of a pin, are turning up in hotels, cruise ships, college dorms and the bedrooms of even the most hygienic homes. Like vampires, bedbugs only come out at night, when they attach themselves to their sleeping hosts for a blood meal. Although the bites may leave a red welt, bedbugs are not known to transmit disease.

It was thought that bedbugs were all but eradicated a few decades ago, before the pesticide D-D-T was banned. As more environment-friendly techniques have developed to manage roaches and other pests, bedbugs have bounced back.

They can live in the tiniest mattress seam, pillows, carpeting or behind loose wallcoverings. Tell-tale reddish-brown spots of blood on a mattress are often the first sign of an infestation.

Bedbugs are most likely to dwell in cities that host large numbers of international travelers. From there, they can hitch a ride in a suitcase to a new home.

If bedbugs strike, you can carefully vacuum or dispose of bedding, repair wallpaper, caulk openings and… if all else fails… call the exterminator.

These days the soothing words of a nursery rhyme just aren’t enough.