Image copyright Louis Sorkin

Scientists have sequenced the entire genome of the bed bug to help work out how to eliminate the pest, which has been developing resistance to existing insecticide sprays.

The findings, in Nature Communications, show how the parasite has adapted to survive by making detoxifying enzymes that destroy pesticides.

And it has grown thicker skin, which helps guard against chemical attack.

But there is a stage in the bug's life when it might be easier to kill.

This is as a young nymph, before it has had its first taste of human blood, according to the two teams of international researchers - one based at the American Museum of Natural History and the other working out of the University of Cincinnati and Baylor College of Medicine, Texas.

Bed bugs survive on a diet of blood alone, and it is not until the pest has begun to feed that some of the genes that govern these self-defence mechanisms against pesticides get switched on.

Another weakness might be their relationship with bacteria that live on, in and around them - their microbiome.

The researchers discovered the bed-bug microbiome contains more than 1,500 genes that probably contribute to their growth and reproduction.

Attacking these beneficial bacteria might prove to be a powerful weapon against bed bugs, alongside new pesticides.

Dr George Amato, one of the study authors from the museum, said: "We have been learning so much about microbiomes recently, and we know that it's not just that micro-organisms live on and in individuals, but in many ways play a critical role.

"This might provide a vulnerability we can use."

Some of the work is part of a project called i5k - an ambitious initiative to sequence the genomes of 5,000 arthropod species, to benefit medicine, agriculture and ecology.