UNIVERSITY PARK, Pa. — There are gall wasps at every Penn State campus, but could you identify one?

A new exhibit at the Frost Entomological Museum is aimed at cultivating awareness about gall wasps and showcasing their beauty and diversity. The exhibit also highlights current research on these insects by faculty in the Department of Entomology in Penn State’s College of Agricultural Sciences.

“Gall wasps are everywhere, and yet very few people in North America have been working on understanding their biology,” said Andrew Deans, professor of entomology and director of the museum.

The department received funding from the National Science Foundation for a project to study gall wasp evolution. There are about 1,500 known species, which are classified in the family Cynipidae, but their evolution is not well understood.

“Most of these species can manipulate plants and coerce them into producing tumor-like structures called ‘galls,’ which serve as a food source and a home for the wasps’ larvae,” Deans said.

He described the diversity of gall architecture and form as “astounding.” Some galls produce nectar, similar to a flower. Other galls have hair-like structures or spines covering them. Galls can resemble a rattle, with the larval chamber rolling around inside a hollow ball.

Some gall wasp species specialize on roses, asters or other herbs. However, most gall-inducing species specialize on oak trees.

“We don’t know how these insects are able to manipulate plant growth and development,” Deans said. “Our preliminary data suggest that for most gall wasps, the plants’ response to venom is what kicks off the growth of a gall. Decoding that process could shed light on basic plant physiology and how to influence these processes.”

Galls also play important roles in the broader ecosystem. Other insects, especially ants, have complex interactions with galls, and the galls themselves influence plant biology in surprising ways. Even humans have used galls for multiple applications.

“About a century ago, some kinds of galls were harvested for livestock feed,” Deans said. “Other kinds of galls were used extensively as a source for the acids needed to tan leather and make ink. I find it incredible that so much biodiversity remains undescribed and unnamed. We have discovered what might be a dozen or more new species of gall wasp right here in Centre County, several of which were right in my backyard.”

Laura Porturas, assistant curator at the Frost Entomological Museum, said, “Often when we talk with people about galls, they recognize them from trees around campus or on plants in their yard but don’t know what they are. Through this exhibit, we share a small part of the strange world of Cynipid wasps and the galls they form. It is just fun to be able to share with people their strangeness and beauty.”

The Frost Entomological Museum houses the insect and related arthropod collections of the Department of Entomology and its partner institutions. The collection is comprised of approximately 1.3 million specimens, with particularly strong assortments of sucking lice, dragonflies and damselflies, aphids, and regional pollinators. The collection serves as a resource for research and supports science education for undergraduate courses across multiple colleges at Penn State.

“It’s an excellent space to easily engage with the strange and wonderful world of insects,” said Porturas. “It shares information about insects and their place in the world, as well as the various research programs and activities currently taking place in the Department of Entomology.”

Visitors to the museum also can pick up a handy field guide on local gall wasps.

Other Penn State collaborators on the exhibit included entomology faculty members John Tooker and Heather Hines; Luke Gasper-Markel, former undergraduate researcher in the Hines lab; and multimedia specialist Michael Tribone. Matt Bertone, of North Carolina State University, and Miles Zhang, of the University of Edinburgh, also contributed.

“We have a whole team of people studying galls at Penn State,” said Deans. “Louis Nastasi and Charles Davis are conducting their Ph.D. research on galls. They are focusing on gall wasps that can be reared from prairie plants and raspberries and related plants, respectively.”

Antoine Guiguet, a postdoctoral scholar from the Department of Biology, also worked on the project. His research, which revealed that venom glands contribute significantly to gall induction, generated many pictures for the exhibit. Antonio Casadei, a Penn State alumnus, was the project’s postbaccalaureate scholar and worked on understanding different species of oak gall wasps.

The Frost Entomological Museum, located at160 Curtain Road on the University Park campus, is open Monday through Friday from 10 a.m. to 4 p.m., except on University holidays.