SACRAMENTO REGION, CA (MPG) - Suds for a bug? A bug for some suds?

The annual “Beer for a Butterfly” contest, launched in 1972 by butterfly guru Art Shapiro, now a UC Davis distinguished professor emeritus, started on 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 is declared the winner, will receive a pitcher of beer or its equivalent.

The contest’s goal "is to get the earliest possible flight date for statistical purposes,” said Shapiro, who has monitored butterfly populations in Central California since 1972 and maintains a research website at butterfly.ucdavis.edu. Shapiro’s scientific research involves long-term studies of butterfly life cycles and climate change. 

Assisting with the 2025 contest is the Bohart Museum of Entomology, directed by Professor Jason Bond, who is the Evert and Marion Schlinger Endowed Chair, University of California, 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 [email protected], 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 won in 2016. The first three were his graduate students.

Shapiro won the 2024 contest, spotting a cabbage white at 11:30 a.m. Jan. 29 in West Sacramento, Yolo County, and saw the same one again at 11:40 a.m.  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 might be faint or not visible in the early season). 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 upper side tend to be faint or even to disappear really early in the season.”

P. rapae is emerging 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,” said Shapiro. 

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 Ph.D. in ecology from University of California-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. 

Most of the first-of-the-year butterflies were found in Yolo County, either in West Sacramento, University of California, Davis campus or nearby. The last winner from Solano County was near the Suisun Yacht Club, Suisun City, at 1:12 p.m. Jan. 25, 2019.  

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

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-19 pandemic but Shapiro recorded his first-of-the-year P. rapae at 1:25 p.m. Jan. 19 in West Sacramento

2021:  No official contest due to the COVID-19 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. 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. 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.