Most people hope never to lay eyes on a bedbug. But one team of researchers spent 15 years scouring guano-filled caves, cliffside nests and museum archives for bedbug specimens that might clarify the murky natural history of this globally loathed parasite.

The team’s findings, published Thursday in Current Biology, confirmed that bedbugs originated at least 100 million years ago, when dinosaurs roamed Earth. The discovery upends the established timeline of bedbug evolution, and could help to anticipate the pest’s next moves in an era of climate change and expansive human activity.

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The research team also found that the main varieties of bedbugs linked to humans evolved some 47 million years ago. Because they are tens of millions of years older than humans, their origins must not be linked to the emergence of Homo sapiens, as past studies have suggested.

To reconstruct the complex evolutionary story of bedbugs — a family of insects known as Cimicidae — the team analyzed the DNA of 34 species, sourced from 62 locations.