Peter Fimrite, SAN FRANCISCO CHRONICLE
The sudden appearance of buzzing insects around Brian Hildebidle’s feet as he surveyed a dune restoration project in the Presidio last week startled him and prompted alarming visions of volunteer workers fleeing from angry yellow jackets.
The stewardship coordinator for the Presidio Trust was about to run when he noticed the insects were a grayish color and swirling in a strange pattern close to the ground.
“I was really curious because I had never seen that flying pattern,” said Hildebidle, who leads volunteers on weekly weed-pulling and planting expeditions and is quite familiar with the park’s bug denizens.
The insects, which he said numbered in the hundreds, turned out to be silver digger bees, a rare sand-loving species that had not been seen in San Francisco in significant numbers for the better part of a century.