Ancient mosquito fossils suggest males once fed on blood, challenging evolutionary assumptions

In what is now Lebanon, millions of years ago, a cluster of small mosquitoes became trapped in tree resin. The resin hardened into amber, sealing the insects inside like specimens in glass. About fifteen years ago, paleontologist Dany Azar found them. He set the slides aside without much fanfare—they seemed to belong to a group of insects outside his main focus, which was tracking how plants and their animal pollinators evolved together.

Only recently did Azar return to examine those old slides carefully. What he found rewrote a piece of insect history. The amber, dated to 125 million years ago, holds the oldest known fossils of the Culicidae family—the mosquitoes. These specimens come from the early Cretaceous, the age of dinosaurs, when flowering plants were just beginning to spread across the world. The Lebanese amber, rich with preserved life from that era, had been holding this secret the whole time.

But the real surprise was structural. The male mosquitoes in the fossils possessed claw-like appendages called claspers. These structures, Azar and his colleagues reasoned, suggest something that contradicts everything scientists thought they understood about mosquito evolution. The males appeared to have the anatomical equipment for piercing skin and drawing blood—something only female mosquitoes do today.

For decades, the scientific consensus held that ancestral mosquitoes fed on nectar, like their modern males still do. According to this theory, females alone evolved the specialized mouth parts needed to pierce skin and extract blood, a risky strategy they employ only when they need extra protein to produce eggs. The males never developed this ability. It seemed logical: blood-feeding is dangerous. A swatted mosquito is a dead mosquito. Why would evolution equip males with such a liability when they don't need the protein for reproduction?

Yet the fossils suggest a different history. If male mosquitoes 125 million years ago possessed structures capable of blood-feeding, then perhaps the ancestral mosquito—before the split between males and females—could feed on blood. Perhaps, as flowering plants proliferated and became abundant, that blood-feeding capacity simply became unnecessary and was lost over millions of years of evolution. "Originally, the mosquito could suck blood," Azar told the New York Times. "With the emergence of flowering plants, this function could simply be forgotten later during the evolution of these insects."

The evidence is not yet conclusive. The claw-like structures in the fossils differ from anything in modern mosquitoes, and it remains possible they served a different purpose entirely. More research is needed to confirm whether these ancient males actually used their claspers to feed on blood, or whether they served some other function now lost to time. What is certain is that the question itself has shifted. Researchers are no longer asking whether females evolved blood-feeding from a nectar-only ancestor. They are asking why, if blood-feeding was once common to the species, it disappeared from males and persisted only in females. The answer may reshape how we understand not just mosquito evolution, but the way insects adapt when their world changes.