Hundreds of thousands of red baby crabs are invading the Cayman Islands in a seasonal migration that residents say is unusually heavy this year.

The crabs are blanketing roads, scurrying across yards and scratching their way up homes and buildings in a process that scientists say will last about a month.

"People living in the coast will have them everywhere," said Tim Austin, deputy director of the Cayman Islands' Environment Department, on Wednesday. "They get in houses, into your AC system. Anywhere there's a gap, they'll find it. They're trying to get somewhere where they'll live happily."

The baby crabs, which are smaller than a thumbnail, were born in the ocean a few weeks ago and are emerging along rocky shores, seeking forests and wetlands near the coast where they will remain until they reproduce and head back to sea to deposit their eggs, Austin said. While the babies are red, the species is known as the black land crab because of the dark purple color it takes on as it ages.