Swarms of tiny beasts nicknamed " mini sharks " with an appetite for human flesh are targeting bathers as they take a swim in the sea.
The bugs were identified as water-line isopods which although are a tiny 0.3inches long, can swarm in groups of 10,000.
They are known to migrate up the west coast of the US.
As a result, people relaxing in the sunshine in California have complained the little blood suckers are attacking their toes as they step into the ocean.
Owing to the strength of their tiny jaws, several manage to draw blood, leaving people feeling sickened, Fox News reported.
One person who encountered a swarm of the bugs described the experience as though she had been mauled by a fearsome piranha.
San Diego resident Tara Sauvage told CBS8 : "It was painful.
“I jumped out of the water and this was so shocking. I had blood all over my foot and in between my toes.
“I pulled my foot out. I had blood all over my foot. It was like small piranhas had bit me.”
Professor Ryan Hechinger, from the Scripps Institution of Oceanography, told the publication the mini beasts “like to eat fresh meat”.
They often look for the carcasses of dying or dead animals on the coastline.
However the tiny bugs are a crucial part of the ecosystem, chewing up rotting fish.
It comes as a “biblical” swarm of flies descended on tourists as they tried to enjoy a day at the beach.
Dozens of people spent their time at the beach frantically swatting away the unwelcome insects on Blackpool seafront.
The seaside town was packed with visitors who were in attendance to enjoy the Blackpool Air Show.
However, the crowds were left to reach for hats and newspapers in an attempt to swat away a group of sandflies that one witness compared to one of the 10 Plagues of Egypt.
Sandfly bites cause small, itchy red bumps that can last for up to a week.
Lindsay King, from Penrith in Cumbria, said: "It was hilarious, everybody was flapping around. It was biblical - like one of the 10 plagues.
"We were all waiting for the Typhoon display and then all of a sudden they just appeared. They came up over the bars and that was it - they hit the whole of the seafront at once and everyone was swatting away at them.
“It was really weird because one minute there was nothing there and the next it went crazy."
