Halloween comes early for Arboretum oaks

Photo of entomology student Laurie Casebier with insect aspirator and mobile laboratory.

Laurie Casebier, undergraduate entomology student, demonstrates using her insect aspirator. She uses this device to document the type and location of wasps she finds during her study.

If you’ve strolled through the Arboretum lately then you’ve probably noticed intermittent ghost-like gloves covering the tips of oak tree branches. No, those are not DIY tree decorations; they are wasp collection receptacles and all are a part of an independent study project being conducted by undergraduate entomology major Laurie Casebier in collaboration with UC Davis’ Bohart Museum of Entomology.

Casebier, who cannot remember a time she wasn’t fascinated with insects, is studying Neuroterus saltatorious, also known as California jumping gall wasp. She travels around the Arboretum courtesy of her mobile laboratory—a large tricycle complete with a trunk of insect-catching goodies—which supplies her tools for inspecting, collecting and recording her findings.

“When female California jumping gall wasps lay eggs on oak leaves, a gall forms and provides the egg moisture, food and cover—among other things—until it is ready to emerge as a fully grown adult,” explains Casebier. “However what also often happens is that other wasps use this gall to deposit their own eggs. The larva(e) from these eggs then parasitize (kill) the gall maker’s larva(e).  Which species parasitize the galls and when? We’re not really sure.”

The outcome of what Casebier is attempting to provide is a chronological story for what wasps parasitize the California jumping gall wasp and when. So, for hours every week she gathers the wasps that hatch from the branches she has bagged, then she identifies and documents them. Sound dangerous? Not really.

“These aren’t the wasps we are used to ruining our picnics,” jokes Casebier. “These wasps are incredibly small, even smaller than fleas. If you ever were stung by one of these wasps, you’d never know it.”

Photo of white organza insect gathering bags on oak trees in the UC Davis Arboretum.

White organza bags cover the tips of oak trees intermittently throughout the Arboretum. The contents of these bags are documented by Casebier for her gall wasp study.

Laurie gathers them by sucking (yes sucking) them from her aspirator—the stethoscope-like object she keeps around her neck—and depositing them into a glass canister. The empty galls that fall from the leaves and get caught in her organza-like collection bags are also separated and kept in case something unexpected should emerge at a later date.

Photo of gall that is the subject of UC Davis undergraduate entomology student's study.

Casebier points to a gall formed by the California jumping gall wasp. This type of gall is not the apple-sized variety and is usually  found only on the underside of leaves.

“Who knows? There could be anunexpected type of wasp or even another species that emerges from these galls,” claims Casebier. “There’s so much to learn from insects, their relationships with each other, and us. Every single tree is home to thousands of tiny tenants, each of which is intricately involved in supporting a role in our environment.”

Casebier’s energy and enthusiasm for her studies are inspiring. Despite the hours of field work involved in her research she enjoys the interaction she has with the public while making her collection rounds.

“Every time I’m out I spend at least an hour sharing what I’m doing with passersby,” explains Casebier. “Most had no idea what galls were or that there were so many types of wasps! I’m so lucky to be able to engage and share what I’m doing with the community and that I have access to such a well-loved and cared for living laboratory in my backyard.”

Although the eggs of the wasps Casebier is studying do not adversely affect the health of these trees, some galls do. Casebier hopes that her project will one day be part of a larger understanding of how wasps and their galls impact tree health.

When not gathering research subjects in the Arboretum, Casebier can be found at the Bohart Museum of Entomology working with her advisors Lynn Kimsey, museum director and Steve Heydon, curator and collections manager, or at one of the many free educational programs offered by the Arboretum.

The Arboretum, as well as other campus landscapes, are consistently in use by our community of faculty, staff, and students for everything from research to recreation. For more information, visit http://arboretum.ucdavis.edu/education_and_research.aspx.


Student testimonial: Jonathan L. Su

Photo of Jonathan Su, student from the UC Davis Arboretum and Public Garden's Learning by Leading Center for the Environment

Jonathan L. Su, Arboretum Ambassador and student employee with the UC Davis Arboretum and Public Garden

“A landscape architect designs experiences for people through the use of physical and natural materials in a space. As a student in landscape architecture, I really wanted to know who these people were and the different materials they used in crafting experiences in space. The UC Davis Arboretum and Public Garden  provided the perfect place for me to work with the Davis community and plants from around the world, in a realistic and ever-expanding setting. Volunteering, interning, and working with the Arboretum and Public Garden turned out better than I could ever imagine.

In the Arboretum Ambassador program, I worked with other ambassadors to creatively use the arboretum space to educate and engage community members ranging from university students to families. From there, I joined the staff. None of my college experiences can really compare to being hired as a landscape assistant with the Arboretum. I developed a pretty intimate understanding of the materials by working with them in the blazing, dry summers months and cloudy, wet winter months of the year.

Although the Arboretum is full of beautiful plants, the most colorful part of the arboretum were the staff and volunteers I worked with every day. From the beginning, I was introduced to passionate, professional individuals who were a huge pleasure to work with and learn from. I found this community of people invested in both my professional and personal growth. They helped me better understand the type of leader I was and supported me at times when life proved particularly difficult.  This community of people helped me to acknowledge my potential and gave me opportunities to recognize it for myself.

Working in the Arboretum helped me understand that although I can’t do everything, I have developed the tools and confidence to give it a try in my own way. I am so grateful for the opportunity to have worked in the UC Davis Arboretum during my time in Davis. Although I will always cherish my experiences and everything I learned about horticulture and community engagement, most importantly I will cherish how much I have learned about and developed myself along the way.”

Jonathan L. Su
Arboretum Ambassador and student employee
UC Davis Arboretum and Public Garden
Landscape Architecture + Environmental Design, B.S. 2015

Conference features campus water conservation expertise

Photo of Matt Forrest speacking at the PGMS conference on water conservation in landscapes and sports fields.

Matt Forrest, irrigation supervisor for the UC Davis Arboretum and Public Garden’s Grounds and Landscape Services team, introduces Don Franklin, specification manager from Hunter Industries who spoke about maintaining a holistic approach to landscape water conservation.  

August 3-5, 2015 our Grounds and Landscape Services team, part of the UC Davis Arboretum and Public Garden, hosted the Professional Grounds Management Society (PGMS) School of Grounds Management Summer Conference.

Participants from around the nation attended not only to learn more about Water Conservation for Landscape and Sports Fields, the conference theme, but to tour our campus–one of two 4-out-of-4 star landscape management and operations accredited campuses in the country. LEARN MORE.

The schedule included the following talks from members of the Arboretum and Public Garden team:

Landscape History and Landscape Design for a Sustainable Future
Skip Mezger and Christina Reyes, Landscape Architects, UC Davis Campus Planning and Landscape Architecture

Managing and Maintaining your Campus Assets (Trees)

Melanie Gentles, Arborist, UC Davis Arboretum and Public Garden (Grounds and Landscape Services)

Drought Tolerant Plants for Northern California
Campus Tour and UC Davis Arboretum Nursery Talk
Taylor Lewis, UC Davis Arboretum and Public Garden

Congratulations to our Grounds and Landscape Services team for developing and managing this valuable educational event and for sharing your many successes with a nationwide audience.

It’s great to see your work and expertise appreciated by so many!


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