Update Jan. 2: Professor Art Shapiro says he caught a cabbage white butterfly on New Year's Day — but his annual beer-for-a-butterfly contest is still on. The Pieris rapae that he caught in West Sacramento "is unambiguously of the fall brood," he wrote in a Jan. 1 email. "As in past years when the fall brood 'slopped over' into January, I will NOT declare the contest over until the 'real' 2013 emergence is documented — which I suspect will not be for 10 days or two weeks, but I will be looking." Shapiro also reported on seeing a Red Admiral (Vanessa atalanta) on Jan. 1, tying the previous New Year's Day record (including last year).

•••

Cabbage white butterflies, beware! Professor Arthur Shapiro and his graduate students, nets in hand, are coming after you again.

It’s time for Shapiro’s annual beer-for-a-butterfly contest, not just any butterfly, but the first cabbage white (Pieris rapae) of the new year.

Shapiro, a distinguished professor in the Department of Evolution and Ecology, runs the contest to aid in his studies of biological response to climate change. He said the cabbage white is emerging in this region a week or so earlier on average than it did 30 years ago.

The contest is open to anyone, including Shapiro, who, by the way, usually wins. He won the 2012 contest by snagging a cabbage white on Jan. 8, the second earliest catch date in the contest’s 40-year history.

The winner receives a pitcher of beer, or the cash equivalent. If Shapiro wins, you can bet he’ll buy the beer anyway!

The rules state the butterfly must be captured outdoors in the counties of Yolo, Solano or Sacramento, on or after Jan. 1, 2013, and the specimen must be an adult. It must be brought in alive to the Department of Evolution and Ecology, 2320 Storer Hall, 8 a.m. to 5 p.m. Monday through Friday, with full data (exact time, date and location of capture) and your name, address, phone number and-or e-mail.

If you catch a cabbage white on a weekend or holiday, hold the specimen in a refrigerator (do not freeze) until you can get the butterfly to Storer Hall. A few days in the fridge will not harm the butterfly.

The cabbage white occurs in vacant lots, fields and gardens with weedy mustards — the butterfly’s host plant. The cabbage white is is typically one of the first butterflies to emerge in late winter.

Since 1972, the first flight has varied from Jan. 1 to Feb. 22, averaging about Jan. 20. Shapiro attributed 2012’s unusually early first catch, Jan. 8, to the prolonged midwinter dry spell.

For more information, contact professor Shapiro, (530) 752-2176 or amshapiro@ucdavis.edu.