The annual “Beer-for-a-Butterfly” contest, also known as “Suds for a Bug,” is still seeking its first winner of 2026. The event, organized by UC Davis Distinguished Professor Emeritus Art Shapiro, has been running since 1972. Shapiro offers a pitcher of beer or an equivalent prize to the first person who collects a live cabbage white butterfly (Pieris rapae) within Sacramento, Yolo, or Solano counties.
Shapiro described his anticipation for this year’s contest: “I just dreamed that I spotted what was probably the first rapae of the year, in West Sac, from a car speeding westbound on West Capitol Avenue, with no chance to stop to validate it! First time I ‘won’ the contest in my sleep.”
The purpose of the contest is scientific. According to Shapiro, “The point of the contest is to get the earliest possible flight date for statistical purposes.” This data supports his long-term research into butterfly life cycles and climate change.
Pieris rapae is common in vacant lots, fields, and gardens where plants in the mustard family grow. Its larvae are considered pests on crops such as cabbage, broccoli, cauliflower, kale, Brussels sprouts, collards, and mustard greens.
Shapiro has tracked local butterfly populations since 1972 and maintains a research website at http://butterfly.ucdavis.edu/. He typically wins his own contest; however, UC Davis graduate students have claimed victory four times since its inception. In recent years—2025 through 2022—the winning butterflies were found in West Sacramento by Shapiro himself. Previous winning sites include locations across Yolo and Solano counties.
In 2016, UC Davis graduate student Jacob Montgomery caught the first butterfly in West Davis and celebrated with Shapiro over a beer at The Graduate.
Those who believe they have collected this year’s first Pieris rapae or who seek more information are encouraged to contact Shapiro via email at theochila@gmail.com or amshapiro@ucdavis.edu.
