Typically Pica Pica outbreaks last anywhere from two weeks to a month. Make sure to wear lots of Sunblock so they slide off your skin. Also a small bottle of vinegar in your dive bag will help in case you get stung, just pour over the area.
Belikin Bill-Thanks for the link. I grew up on the coast surfing and swimming, and have had these bothersom parasites more times than I care to remember, just never heard of them being called Pica Pica.Interesting.