Stunning: Blood found in belly of 46-million-year-old mosquito

Next time you’re annoyed by a buzzing mosquito or scratching a mosquito bite, you perhaps can take a bit of comfort in the fact that these pests have been annoying our human ancestors long before our furry forbears ventured out of the treetops onto the savannah and tried a walking-upright lifestyle. Researchers now have the proof in a unique, recently discovered 46-million-year-old fossilized female mosquito with a visibly distended abdomen containing the components of red blood cells.

The researchers, led by Dale Greenwalt from the National Museum of Natural history, discovered the mosquito–only about two-tenths of an inch in size–trapped in oil shale from an ancient lakebed in northwestern Montana. They say the odds of finding one preserved in this way are astronomical.

“The insect had to take a blood meal, be blown to the water’s surface, and sink to the bottom of a pond or similar structure to be quickly embedded in fine anaerobic sediment, all without disruption of its fragile distended blood-filled abdomen,” the researchers said in their study published in the Proceeding of the National Academy of Sciences.

Greenwalt’s team used mass spectrometry to detect the presence of iron and porphyrin molecules, which are two components of heme, the protein that carries oxygen in red blood cells. This confirmed that the iron came from the mosquito’s last meal and was not an artifact of the fossilization process. Mass spectrometry can only be used on flat surfaces and so cannot be used to analyze insects trapped in amber, the material in which most fossilized bugs are found, researchers say.

The blood-engorged female specimen–only females drink blood–was one of 36 mosquitoes recovered from the Kishenehn Formation, fossil grounds located near the Flathead River along the western boundary of Montana’s Glacier National Park.

Although Greenwalt has been collecting pieces of shale from the area for years, the mosquito specimen described in the study did not come from one of his expeditions; instead it came from a collection of insects that had been gathering dust in the basement of former graduate student Kurt Constenius since the 1980s. When Constenius donated his collection to the Smithsonian, Greenwalt saw the mosquito and immediately knew it was different, as Agence France-Presse (AFP) reports.

Because research has shown that DNA cannot survive for longer than about 6.8 million years, no genetic material could be extracted from the team’s ancient mosquito specimen. Greenwalt told AFP that it’s possible the blood came from a bird, as the insect resembles a modern-day mosquito from the genus Culicidae, which tends to feed on avifauna. “But that would be mere speculation,” Greenwalt said.