UC Davis distinguished professor emeritus Art Shapiro. (Photo by Kathy Keatley Garvey)

The annual “Beer for a Butterfly” contest, launched in 1972 by butterfly guru Art Shapiro, now a UC Davis distinguished professor emeritus, gets underway Jan. 1.

The first person to find the first live cabbage white butterfly, Pieris rapae, of the year in the three-county area of Sacramento, Yolo and Solano--and follows the submission rules--will receive a pitcher of beer or its equivalent.

Shapiro, who has monitored butterfly populations in Central California since 1972, and maintains a research website at http://butterfly.ucdavis.edu/, says the point of the contest "is to get the earliest possible flight date for statistical purposes.” It's all part of his scientific research involving long-term studies of butterfly life cycles and climate change. 

Assisting with the 2025 contest will be the Bohart Museum of Entomology, directed by Professor Jason Bond, who is the Evert and Marion Schlinger Endowed Chair, UC Davis Department of Entomology and Nematology, and associate dean, UC Davis College of Agricultural and Environmental Sciences. 

The 2025 contest rules stipulate that contestants must collect a live butterfly in the wild, video it, and email the entry to the Bohart Museum at bmuseum@ucdavis.edu, listing the time, date and place. The insect must be an adult—no caterpillars or pupae—and must be captured outdoors, Shapiro said.

The professor also participates in the contest. In fact, Shapiro has been defeated only four times and those were by UC Davis graduate students. Adam Porter won in 1983; Sherri Graves and Rick VanBuskirk each won in the late 1990s; and Jacob Montgomery in 2016. The first three were his own graduate students.

Shapiro won the 2024 contest,  spotting a cabbage white on Monday, Jan. 29 at 11:30 a.m. in West Sacramento, Yolo County, and saw the same one again at 11:40.  He didn't capture it, but recorded it in his notebook. No one else came forth to claim the prize. 

The butterfly inhabits vacant lots, fields and gardens where its host plants, weedy mustards, grow. What does it look like? It's a white butterfly with black dots on the upperside (which may be faint or not visible in the early season). It inhabits vacant lots, fields and gardens where its host plants, weedy mustards, grow. The male is white. The female is often slightly buffy; the "underside of the hindwing and apex of the forewing may be distinctly yellow and normally have a gray cast,” Shapiro said. “The black dots and apical spot on the upperside tend to be faint or even to disappear really early in the season.”

First flight. P. rapae is emerging earlier and earlier as the regional climate has warmed, Shapiro says.  "Since 1972, the first flight of the cabbage white butterfly has varied from Jan. 1 to Feb. 22, averaging about Jan. 20." 

In its caterpillar stage, P. rapae is a pest. (See cabbageworm on the UC Statewide Integrated Pest Management Program website.)

Matthew Forister, the Foundation Professor, Trevor J. McMinn Endowed Research Professor in Biology at the University of Nevada, Reno, collaborates with Shapiro and annually creates a graph, using statistics from 1972 to the current year. Forister received his PhD in ecology from UC Davis in 2004, studying with Shapiro.

In its larval stage, the cabbage white butterfly is a pest of cole crops, including cabbage, cauliflower and broccoli. 

Recent Beer-for-a-Butterfly Contest statistics:

• 2024: Art Shapiro recorded the winner at 11:30 a.m., Jan. 29 in West Sacramento, Yolo County
• 2023: Shapiro recorded the winner at 11:22 a.m., Feb. 18 in West Sacramento.
• 2022: No official contest due to the COVID pandemic, but Shapiro recorded his first-of-the-year P. rapae at 1:25 p.m. on Jan. 19 in West Sacramento
• 2021:  No official contest due to the COVID pandemic, but Shapiro collected his first-of-the-year at 1:55 p.m. Jan. 16 on the UC Davis campus, Yolo County
• 2020:  Shapiro recorded the winner in Winters, Yolo County at 11:16 a.m. on Jan. 30 at the Putah Creek Nature Park.  
• 2019: Shapiro collected the winner near the Suisun Yacht Club, Suisun City, Solano County, at 1:12 p.m., Friday, Jan. 25.  
• 2018:  Shapiro collected the winner in West Sacramento
• 2017: Jan. 19: Shapiro collected the winner on the UC Davis campus
• 2016: Jan. 16: Jacob Montgomery collected the winner in west Davis
• 2015: Jan. 26:  Shapiro collected the winner in West Sacramento
• 2014: Jan. 14:  Shapiro collected the winner in West Sacramento
• 2013: Jan. 21:  Shapiro collected the winner in West Sacramento
• 2012: Jan. 8:   Shapiro collected the winner in West Sacramento
• 2011: Jan. 31:  Shapiro collected the winner in Suisun
• 2010: Jan. 27:  Shapiro collected the winner in West Sacramento