Flesh-eating Parasitic Wasps Discovered in New York, Spreading Across U.S.

Scientists have identified two newly discovered species of parasitic wasps that are spreading from New York across the country, raising concerns about their impact on ecosystems. The invasive insects, which originated in Europe, are now documented as far as the Pacific coast.

The wasps reproduce by laying their eggs inside oak galls. Once the larvae hatch, they slowly consume the native oak gall wasps living inside, eating non-essential tissues first to prolong the host’s survival before eventually consuming it completely. Female parasitic wasps inject one or more eggs into a host, ensuring the larvae have a live food supply until they mature.

While experts stress that the wasps do not threaten humans, their spread could destabilize natural systems. Researchers believe the species likely arrived in North America through imported oak trees or by stowing away on aircraft, and their populations have since expanded rapidly.

"We did find that they can parasitize multiple oak gall wasp species and that they can spread, given that we know that the population in the west likely spread across regions and host species from a localized small introduction," said Kirsten Prior, professor of biological sciences at Binghamton University, in an interview with The Daily Mail. "They could be affecting populations of native oak gall wasp species or other native parasites of oak gall wasps."

Scientists also warn that the invasive wasps may move beyond oak gall hosts and attack other wasp species that play important ecological roles. Initially thought to be a single species, Bootanomyia dorsalis has now been identified as two distinct types through genetic analysis—B. dorsalis sp. 1 and B. dorsalis sp. 2.

Research shows that the New York population of parasitic wasps displays higher genetic diversity, which could mean they were introduced multiple times. Populations found in Washington, Oregon, and British Columbia show less diversity, suggesting they stemmed from a smaller founding group. The insects’ ability to live nearly a month as adults may explain how they traveled long distances on imported plants or in cargo.

North America is home to around 90 oak tree species and about 800 species of oak gall wasps making the ecosystem particularly vulnerable. A recent study noted, "This finding of multiple introductions into the North American oak gall system – one of them apparently quite well-established across the Pacific coast – makes it reasonable to presume that the portcullis has been raised for parasitic wasp invasions, as it has been for so many other insects."

Flesh-eating Parasitic Wasps Discovered in New York, Spreading Across U.S.