SAVANNAH, Ga. — The mosquitoes that spread the Zika virus are among the hardest species to fight because they live and breed in tub drains, dog bowls, buckets, flower pots and other spots where water collects inside the houses and yards of the people they bite, insect experts noted Monday.

Because they stick close to home, Zika-carrying mosquitoes are hard to target with larvacide and insecticide sprays, they said.

“You’re not going to find them in roadside ditches or in swamps,” said Mark Cothran, mosquito control director for Gulf County, Florida. “You’re going to find them in dog food bowls or in 5-gallon buckets. It almost requires going door-to-door to dump out containers.”

Cothran is one of hundreds of municipal mosquito control officers and insect researchers from across the U.S. attending the American Mosquito Control Association’s annual conference, which opened Monday in Savannah.

He and others noted that while the Zika virus that has spread rapidly in Latin America may be new to the U.S, the two mosquito species known to carry it are not.

Aedes aegypti, the mosquito blamed for the Zika outbreak linked to birth defects in Brazil, can be found in the southern U.S. from Florida to California. Another carrier is the Asian tiger mosquito, Aedes albopictus, which has a more northerly range that includes cities such as Chicago and New York.

U.S. mosquito fighters have already dealt with these species to prevent outbreaks of dengue fever and chikungunya virus, said Joe Conlon, the association’s technical director.

“It’s business as usual, because we know how to control these mosquitoes,” Conlon said. “But in order to get rid of these things, you have to be very fastidious.”

Some cities and counties are already taking steps to get ready before their mosquito breeding seasons begin in earnest this spring.