From 1991 through 2011 the city of Fort Worth, Texas, did not spray for mosquitoes.  The following is a statement that we found on the city website several years ago, explaining very succinctly the case against spraying:

Why Fort Worth has not sprayed for mosquitoes

    West Nile is not just a river in Egypt; it’s now a virus in Texas carried by about one percent of mosquitoes in infected areas. With the virus identified nearby, it’s important that residents understand their vital role in protecting themselves from the threat of infection.

    In extreme cases, West Nile virus causes inflammation of the brain and can be found in humans, birds and other animals in Africa, Eastern Europe, the Middle East and Western Asia. The disease was not identified in the United States until 1999.

    West Nile Virus has been identified in Fort Worth and is here to stay. But according to the Texas Department of Health (TDH), there is no need for panic. West Nile has not been as deadly as St. Louis encephalitis, another mosquito-borne illness that has been in Texas for years.

    Nevertheless, there have been deaths in the U.S., and one death is too many. The Fort Worth Public Health and Environmental Management departments, along with the Tarrant County Health Department and TDH are collaboratively conducting surveillance for mosquito-borne illnesses. Together, our organizations are working hard to lessen the impact of the disease on Fort Worth residents.

    While surveillance and education continues, a critical question arises: what will have the greatest impact in reducing the threat of human exposure to mosquito-borne illnesses: spraying by the city or source reduction and personal protection by residents?

    While some welcome spraying for mosquitoes, the fact is that spraying will not eliminate the threat of mosquito-borne illnesses. This is specifically why the city of Fort Worth discontinued its spraying program in 1991.

    Spraying for mosquitoes has one positive impact—a temporary reduction in the number of adult mosquitoes in the immediate vicinity. But similar to some medications, the toxins used in spraying may have side effects that generally outweigh the limited positive impacts.

    First, spraying chemicals in the streets will not rid the city of mosquitoes. The chemical must make contact with the insect to kill it, making it difficult to destroy mosquitoes hiding in grass, bushes, trees or backyards. Moreover, the chemicals have no residual effects and do nothing to kill mosquito larva thriving in stagnant water.

    Second, spraying for mosquitoes may give residents a false sense of security. The risk of someone being infected with West Nile might then increase if fewer people decide not to use insect repellant before working or playing outdoors.

    Third, adding harmful chemicals to the environment can have unwanted secondary effects to both air and water.

    Lastly, thousands of Fort Worth residents living with respiratory problems such as asthma would be in danger of an outset of symptoms. Asthma and Allergies are two of the top five health problems for Fort Worth residents, according to the 1998 Community Needs Assessment. The potential inhalation hazard to the general population does not seem worth the risk of killing a few mosquitoes.

    All things considered, residents are better positioned to reduce the likelihood of human exposure to West Nile. Until such time when the pros of spraying outweigh the cons, Fort Worth and Tarrant County will continue to promote the importance of the residents’ role in preventing mosquitoes at their source—stagnant water—and in protecting themselves from mosquitoes by wearing appropriate clothing and insect repellant outdoors. It takes three to seven days for thousands of mosquitoes to develop in stagnant water. Anything outdoors that holds water—old tires, outside pet water bowls, unkempt pools, birdbaths, potted plants or clogged rain gutters—is a potential breeding place for mosquitoes.

    The city's plan can be described as a “let’s do-it-together plan.” The city, county and state are doing their part by monitoring for West Nile and providing residents with the information they need to protect themselves. Now it’s the residents’ responsibility to use that information. By taking simple precautions, residents can make a much greater impact on mosquitoes and the threat of West Nile than any mosquito fogger.

    The recent temporary flareup in West Nile virus activity in the state, however, has prompted Tarrant County officials to engage in some fogging in Fort Worth by truck.  We find this action hard to reconcile with the enlightened statement above and wonder if the officials from 20 years ago are no longer in the decision-making loop.