Eucalyptus trees shimmered with flashes of orange and black as an estimated 8,500 monarch butterflies greeted visitors during the official opening of the Pismo State Beach Monarch Butterfly Grove.
People of all ages flocked to the grove Thursday to see the butterflies that have arrived from the western slopes of the Rocky Mountains to spend the winter at the beach.
State Parks Department officials and Central Coast Natural History Association volunteers held a brief opening ceremony for the grove, where a number of improvements were recently completed.
Docents also presented educational programs for all ages and offered children a variety of activities, from making monarch life-cycle bracelets to charting the health of the butterflies’ habitat.
For those who didn’t bring their own binoculars, spotting scopes were set up to provide close-up views of the butterflies hanging in layered clusters on the eucalyptus branches.
As the sun warmed their bodies, the monarchs took to the sky in search of nectar-filled flowers, delighting visitors who snapped pictures of the spectacle.
Although their numbers have declined over the past decade, as many as 25,000 monarchs may stay in the grove on Highway 1 between Grover Beach and Pismo Beach.
Scientists still are uncertain how the monarchs navigate from their summer homes in the Rockies and Canada to wintering sites in California, Florida and Mexico.
The butterflies that began to appear at the Pismo State Beach grove in October are four generations removed from the monarchs that spent last winter here.
Around February, the flock will breed, and their larval offspring will feed on the milkweed that grows in the grove.
Then after spending eight to 12 days in a chrysalis, the larvae will metamorphose into butterflies and leave for summer homes in the Rockies.
Admission to the grove is free. The docents’ trailer, open from 10 a.m. to 4 p.m. daily, offers educational books, jewelry, T-shirts and other butterfly souvenirs.
Special talks about the monarchs are offered at 11 a.m. and 2 p.m. each day, weather permitting.