Millions of zombie crabs are currently migrating in massive swarms after a population boom.

The crabs have emerged early and in unprecedented swarms according to local residents around the Bay of Pigs, Cuba.

Following two years of Covid, the crab’s size and numbers have grown massively because they were allowed to cross normally busy roadways in peace.

After the island’s spring rains begin, millions of red, yellow and black crustaceans emerge at dawn and dusk and march from the forest across the road and down to Cuba’s southern coast to spawn in the sea.

Mass migration occurs after mating because females return to the sea to release their eggs to be hatched where the larvae live as plankton.

“There was very little traffic, and very little tourism,” said Angel Iraola, 46, who guards a parking lot off the winding, crab-infested road that tracks the bay. “There are more crabs now than there have been in many years.”

Reinaldo Santana Aguilar, a scientist with Cuba’s environment ministry analyzed the marked increase in population, saying:

“We have observed that the migrations have had an unusually high density of crabs.”

“It is very likely that the crab populations have recovered and that is why there is such a strong migration now.”

Zombie crabs get their unique name because they are the host organism for two species of flies who gain nutrients, shelter and movement from the crab.

These flies occupy the crustacean for most of their lives and are reluctant to leave.

They lay eggs around the crab’s eyes where the larvae migrate into their host and live there, feeding on naturally produced microbes.

Over time the larvae will move towards the crab’s gill chamber and then the mouthparts before falling to the ground to grow into fully grown flies.

Many crabs often died being crushed by cars in the years before Covid but their sharp shells can easily puncture tires.

Giordanis Duran, 43, was surprised by the huge numbers of crabs this year, but came prepared.

With a homemade mop, he shooed crabs from the road ahead of his car as his family made their way to a local waterfront hangout to celebrate a birthday.

“We use the mop to scare off the crabs so as not to kill them. They are animals,” Duran said, who noted that the tactic also helps ward off flat tires.

Zombie crabs are commonly found in the Caribbean in countries such as Cuba and Barbados.

They are omnivorous scavengers and mostly feed on plants while their predators may include birds.

This article originally appeared on The Sun and was reproduced here with permission.