Scientists identify key shift that led to huge rise in bedbugs

Bedbugs may have been interrupting human sleep for more than 50,000 years, but it was only when humans left caves and formed the first cities that their populations really boomed, according to a new study.

The research, published in science journal Biology Letters, looked at the genetics of bedbugs and found that they split into two lineages thousands of years ago – one that stayed on bats, and one that targeted humans.

By the Ice Age both populations were in general decline, with the bat-associated lineage never bouncing back, but the urban bedbugs recovered and began to thrive as human settlements expanded into cities.

As humans built early cities, such as Mesopotamia, around 12,000 years ago and their populations started to boom, so too did the populations of the tiny parasitic insects feasting on human skin – making the species one of the first human pests.

“That makes sense because modern humans moved out of caves about 60,000 years ago,” said Warren Booth, the Joseph R. and Mary W. Wilson Urban Entomology associate professor.

"There were bedbugs living in the caves with these humans, and when they moved out they took a subset of the population with them so there's less genetic diversity in that human-associated lineage."

"What will be interesting is to look at what's happening in the last 100 to 120 years," Prof Booth told science website Phys.org.

"Bed bugs were pretty common in the old world, but once DDT [dichloro-diphenyl-trichloroethane] was introduced for pest control, populations crashed. They were thought to have been essentially eradicated, but within five years they started reappearing and were resisting the pesticide."

Bedbug infestations saw a dramatic 35 per cent jump between 2022 and 2024, while cockroach removal visits rose by 13 per cent over the same period.