The study was done in mosquitoes bred in the U.T.M.B. insectary, “so we need to confirm whether this occurs in nature, too,” Dr. Tesh said. Answering that question will mean collecting eggs and larvae in the wild from the mosquitoes, Aedes aegypti, that carry the infection.

“Aedes aegypti are hard to find,” Dr. Tesh said. “They aren’t as numerous as other mosquitoes.”

Zika’s relatives in the flavivirus family — including yellow fever, dengue, West Nile, Japanese encephalitis and St. Louis encephalitis — all have the ability to skip down a generation in various mosquito species. But so-called filial infection is usually rare.

In the case of Zika, only one daughter Aedes aegypti mosquito out of 300 inherits the virus from an infected mother, Dr. Tesh’s team estimated.

The team also tested Aedes albopictus, a related species that is more widespread through the United States. The researchers found that no progeny inherited the virus from an infected mother.

By contrast, Dr. Tesh said, filial infection is important for the La Crosse virus, which causes serious brain disease or death in about 72 Americans each year, most of them children. That virus is transmitted to humans by Aedes triseriatus, a forest mosquito that picks it up from chipmunks.

La Crosse virus passes down easily in mosquito eggs; about 70 percent of mosquito females maturing from those eggs inherit the virus, Dr. Tesh said.