Suds for a bug. A butterfly for a beer...
If you find and collect the first cabbage white butterfly in the three-county area of Sacramento, Yolo and Solano, and you are judged the winner of the annual "Beer for a Butterfly" Contest, you will receive a pitcher of beer or its equivalent.
And bragging rights!
UC Davis Distinguished Professor Emeritus Art Shapiro has sponsored the contest since 1972. He has monitored butterfly populations in Central California since 1972, and maintains a research website at http://butterfly.ucdavis.edu/,
Shapiro 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.
In its larval stage, the cabbage white butterfly is a pest known as "the imported cabbageworm." Says the UC Statewide Integrated Pest Management Program on its website: "Cabbageworm larvae chew large, irregular holes in leaves, bore into heads, and drop greenish brown fecal pellets onto edible portions of the leaf."
Want to know more about the larvae? The eggs are laid singly on leaves. "Eggs are pale yellow to orange and are shaped like a football standing on its end," according to UC IPM. "Older larvae may be up to an inch long. Compared with other caterpillars, cabbageworms move slowly and are sluggish but they feed voraciously on both the outer and inner leaves, often feeding along the midrib, at the base of the wrapper leaves, or boring into the heads of cabbage. After 2 to 3 weeks of feeding, larvae pupate attached by a few strands of silk to stems or other nearby objects. Pupae are green with faint yellow lines down the back and sides; there is no spun cocoon. The cabbageworm is active throughout the year in California..."
What does the adult look like? It's a white butterfly with black dots on the upperside (which may 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 says. “The black dots and apical spot on the upperside tend to be faint or even to disappear really early in the season.”
Where can you find it? It inhabits vacant lots, fields and gardens where its host plants in the mustard family (Brassicaceae) grow. Hosts include cultivated vegetables like cabbage, broccoli, cauliflower, kale, Brussels sprouts, collards, and mustard greens.
Shapiro, who competes in the contest, 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.
Recent Beer-for-a-Butterfly Contest statistics:
- 2025: Art Shapiro collected the winner at 12:13 p.m., Jan. 23 in West Sacramento, Yolo County
- 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
Jan. 1 is almost here. Will you be the first to collect a cabbage white butterfly in the three-county area? Contact Shapiro at theochila@gmail.com or amshapiro@ucdavis.edu if you have a prospective winner or need more information.
Cover image: Cabbage white butterfly, Pieris rapae. (Photo by Kathy Keatley Garvey)