If you have been feeling a little itchy after frequenting northwestern Florida beaches in recent days, it could be because of a reported invasion of sea lice.

Pensacola lifeguards hoisted purple flags this week warning beachgoers of dangerous marine life after sea lice were spotted in area waters, WEAR-TV reports.

Sea lice are not really lice at all. That's the colloquial name given to the larvae of thimble jellyfish that typically show up in area waters between April and July.

Swimmers who come into contact with the larvae may feel immediate stinging that transforms into a rash known as "seabather's eruption" several hours later.

The larvae can become lodged between a person's bathing suit and skin, resulting in multiple stings.

(MORE: 3,000 Stung by Jellyfish in 2 Weeks on Florida's Volusia County Beaches )

The Florida Department of Health says it is better to not wear a t-shirt or a one-piece bathing suit in infested waters to prevent the larvae from becoming trapped near the skin. There is also evidence that sunscreen can help protect the skin from stings.

While the rash is little more than an itchy nuisance for most, some people can experience a severe reaction that includes fever, chills, headaches and nausea. The rash typically resolves within seven to 10 days.

Like jellyfish, it's best to treat the stings with vinegar, followed by antihistamines and over-the-counter hydrocortisone creams. Pastes of baking soda and bathing in Epsom salts can also be beneficial.

The agency also recommends that swimmers remove their swimsuits after exiting the water and showering in warm water.

Sea lice have also been reported at beaches in Panama City, Destin, South Walton and Gulf Shores.