What a buzzkill!

Tourists enjoying the holiday weekend at South Street Seaport today were joined by millions of uninvited guests when a swarm of bees took up residence on a fire hydrant outside a Mexican restaurant.

The humming mass of insects — likely an escaped hive from a rooftop bee-keeper somewhere nearby — enveloped the hydrant at the corner of Fulton and Front Streets around 11 a.m. and swarmed for hours before cops arrived.

“It’s unusual, I’ve ever seen anything like this,” said Winston Small, 25, a bartender at the restaurant. “ I don’t think I’ve ever even seen a bee at South street seaport!”

Stunned tourists kept their distance, but couldn’t help being amazed at the scene which has become a regular summertime occurrence as bee-keeping has become a hip, popular hobby among New Yorkers.

“This is mad! I’ve never seen anything like it,” said John Nye, 42, a London horticulturalist on vacation.

“Its nice to have a touch of nature in an urban environment!” he said.