There is an alternative to dumping small containers of standingwater to kill mosquito larvae, according to the Mississippi StateDepartment of Health.

Concern about mosquitoes was heightened this year by theemergence of the West Nile virus among humans. As of Tuesday, therewere 91 confirmed human cases and three deaths attributed to thevirus in the state.

Dewayne Bass of Statewide Pools said he has received “literallyhundreds of calls” from elderly people who say they cannot dumptheir bird baths, fountains or other still water containers becausethey lack the physical strength. He said they are wanting to knowwhat they can do to safeguard their yards.

According to Dr. Brigid Elchos, a public health veterinarianwith MSDH, the most effective solution besides removal is to treatthe still water containers with a mosquito-killing chemical.

Although she said she did not want to endorse any specificproduct, Elchos said there are at least three products availableover the counter at home improvement, pool maintenance and otherstores that are mosquito-specific and have been tested for useagainst mosquitoes by the Environmental Protection Agency.

Mosquito Dunks and Mosquito Bits are both products that containa bacteria that targets mosquitoes and mosquito larvae, she said.Zodiac Preventative Mosquito Control is an insect regulator thatprevents mosquitoes from developing into adults.

All three products, she said, are effective against mosquitoesand will not harm other species.

Elchos stressed, however, that people should closely follow thelabeling directions and not overuse the chemicals.

“Basically the label is (what is allowed by) the law,” shesaid.

Chlorine is an effective chemical for killing mosquitoes insmall containers of water, such as bird baths, Bass said. Birds arenot affected by the chemical concentration of a 3-inch chlorinetablet in a bird bath, he said.

Elchos said she could not recommend using chlorine to targetmosquitoes because she could not be sure of its effectiveness or ofits safety for other species.

“I don’t know the effectiveness of chlorine on mosquitoes,” shesaid.

Well-maintained swimming pools are not susceptible to mosquitobreeding, she said, but she could not attribute that to chlorine.She cited several other factors, such as water pumps and otherchemicals, as possible contributory elements. Moving water causes awave action that kills mosquitoes as they emerge from the larvalstage into young adults.

In other large containers of still water, such as fountains, useof the fountain could be an effective deterrent to mosquitobreeding, but also one that bears some monitoring, Elchos said.

“As long as the fountain is aerated and moving, it is safe,” shesaid.

A continuously running fountain should kill any mosquito thattries to breed there, she said, but one that is run at certainintervals may need to be closely monitored to ensure it is notbreeding mosquitoes. If a check determines there is no larva in thefountain, Elchos said, it should be running frequently enough tomake it inhospitable to mosquitoes. She recommended checking itdaily.

“There’s no need to treat if there’s no larva there,” Elchossaid.

In more temporary cases, two 3-inch chlorine tablets used in a30,000 gallon swimming pool will last about four days, Bass said.The length of effectiveness may be diminished by several factors,he said, including heat and the addition of fresh water, such asrain. One tablet would be more than enough to treat a normal-sizedbird bath, he said.

He said he has treated numerous bird baths with chlorine andseen its effects. He said he knows it kills mosquito larvae.

“That may be true,” Elchos said. “I can’t really say what effectchlorine has. I would recommend using a mosquito-specificproduct.”