Bedbugs have been around for much longer than you thought. Until now, the oldest known fossils of “cimicids” were 3,500 years old, which were unearthed in Egypt in 1999. A new study shows that the oldest cousins of modern bedbugs lived in the Paisley Caves of Oregon nearly 11,000 years ago. The same caves also hold some of the oldest evidence of human activity in North America.

Bedbugs
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14 individual bedbugs found in Paisley Cave 2

According to a study published in the Journal of Medical Entomology on April 4, researchers were investigating the Paisley Five Mile Point Cave site when they found fossils of bedbug relatives in Cave 2. Researchers recovered a total of 14 bedbugs from the site. The fossils range between 5,100 and 11,000 years old, scientists said after analyzing their age using carbon dating.

Lead researcher Martin Adams compared the fossils to insects in the library of the University of Oregon Museum of Natural and Cultural History. It was difficult to identify the ancient cimicids because the classification system is based on the whole insect. In some cases, the bedbugs were too fragmented to be identified. Of the 14 individuals, Martin Adams and co-author Dennis Jenkins identified five as Cimex pilosellus, three as C. latipennis, and one as C. antennatus.

The other five individuals could not be identified, though scientists confirmed that they belonged to the genus Cimex. Researchers said 11 of the 14 individuals were females, while the gender of the other three could not be determined. Adams told Live Science all three species were native species. They lived off bats, which were also found in the Cave 2.

The caves were seasonally occupied by humans

Today, there are three bedbug species that have evolved to parasitize humans: Cimex lectulariusC. hemipterus and Leptocimex boueti. Adams said the species recovered from Paisley Caves couldn’t survive to feed on modern humans. The ancient cimicids didn’t have any rigid host preferences. Though the bedbugs lived off bats, they would have fed on humans as well if the opportunity presented itself.

Scientists believe such an opportunity must have occurred many times because the Paisley Caves were seasonally occupied by hunter-gatherers. The cimicids do not fly. They would have fed on whatever host was the closest, including humans. Previous studies have shown that Cimex lectularius and Cimex hemipterus evolved to become humans parasites in caves, which our ancestors shared with bats.

Why didn’t the Oregon bugs survive?

When humans moved beyond the cave environment, the bugs went with them and adapted to new environments to become “cosmopolitan human pests.” Now comes the big question: Why didn’t the Paisley bugs follow their human hosts out of the cave environment? Scientists speculate the human populations might have been too small to help the cimicids survive in the long run, or the bedbug population itself might have been small.

The study shows that there could be many more species of bedbugs that we do not know about yet.