It's happened again. Cuba's Bay of Pigs has been overrun, this time not by US-backed anti-Castro forces, but by millions of red, yellow and black landcrabs.

Each year, after the first spring rains, the crabs march for days from the surrounding forests to the bay on Cuba's southern coast to spawn in the sea, wreaking havoc along the way.

At dawn and dusk they emerge, scuttling sideways toward the sea, climbing up house walls and carpeting the coastal road that curves around the bay. The stench of crushed crab fills the air and their sharp shells puncture car tires.

"Thirty to 40 can enter without you even realising it," said Edian Villazon, who runs a food hut opposite the sea, which does not serve up crab meat. Cubans believe this type is toxic. "We have to always keep the door shut."