MIAMI — Florida has found the Zika virus in three groups of mosquitoes trapped in Miami Beach — the first time this has happened in the continental U.S. — and authorities are blaming a particular flower for making mosquito control much more difficult.

One of the traps that tested positive was at the Miami Beach Botanical Gardens, where bromeliads bloom. The plants trap standing water in their cylindrical centers, providing excellent breeding areas for mosquitoes amid their colorful flowers and pointy leaves.

“Everyone should know by now that bromeliads are really problematic for us. These are probably the number one breeding area for mosquitoes,” said Miami-Dade County Mayor Carlos Gimenez.

He said Miami Beach is removing all bromeliads from its landscaping, and urged residents to either pull them out or rinse them after every rain.

With Hurricane Hermine bringing much more rain to Florida, Gov. Rick Scott on Thursday ordered the county to immediately conduct aerial spraying as recommended by the CDC.

The Zika-carrying mosquitoes were trapped in a touristy 1.5-square-mile area of South Beach identified as a zone of active transmission of the virus, the Florida Department of Agriculture and Consumer Services said.

“This is the first time we have found a Zika virus positive mosquito pool in the continental United States,” confirmed Erin Sykes, a CDC spokesman.

Finding the virus in mosquitoes has been likened by the U.S. Centers for Disease Control and Prevention to finding a needle in a haystack, but the testing helps mosquito controllers target their efforts, and it confirms that the insects themselves, in addition to infected humans, have begun transmitting the virus inside the mainland U.S.

The illness spreads from people to mosquitoes to people again through bites, but the insects do not spread the disease among their own population, and their lifespan is a few weeks.

A poll released Thursday suggests nearly 48 percent of Americans are wary of traveling to U.S. destinations where people have been infected.

Most of the Zika infections from Florida mosquitoes have been in the Miami area, not the tourist mecca of Orlando and its Walt Disney World, Universal and SeaWorld theme parks.