US researchers have uncovered the genetic mechanism that bed bugs use to resist powerful insecticides, according to a study, leading to the hope of more effective ways to combat the pests.

Bed bugs, which have been largely absent from the United States since the 1950s, have returned in force in the last decade in the US, and notably other Western countries in Europe.

They have, in this time, developed unique resistance to the insecticides that are mainly used against them -- deltamethrin and beta-cyfluthrin, both leading pyrethroids.

The genetic research released Wednesday in the journal PLoS One, published by the Public Library, offers new hope to understand their resistance and find new ways to eradicate the blood-sucking bugs.

"Different bed bug populations within the US and throughout the world may differ in their levels of resistance and resistance strategies, so there is the need for continuous surveillance," said lead author Zach Adelman, associate professor of entomology at Virginia Tech.

Adelman and the other researchers in the study assessed two populations of bed bugs -- "a robust, resistant population" found in 2008, and a "non-resistant population" that has been raised in a lab since 1973.

The study determined how each strain succumbed to the pyrethroids, if at all, and determined that over a 24 hour period it required "5,200 times more deltamethrin or 111 times more beta-cyfulthrin" to kill the modern bed bugs compared to the older specimens.

The bed bug's bite is a little painful rather than dangerous, but many people are scared because the creature mainly attacks when people are asleep.