Spraying makes a bad problem worse

When reports of West Nile virus appear in the news and drought-driven mosquito populations increase, there is a tendency by well-meaning residents to call for community-wide spraying. In turn, well-meaning city officials want to be seen as addressing the problem. Trucks driving through neighborhoods in the early morning hours with flashing lights and loud spraying equipment can be offered as camera-ready proof that residents’ concerns are being dealt with. Unfortunately, the toxic trucks aren’t merely ineffective; they make the health problem worse.

  • Spraying efforts take resources that could be used to actually reduce mosquito habitat.  These resources are instead spent on “mosquito-control theater” — giving the false illusion of reducing mosquito-borne-disease risk while doing little to actually secure public health.
  • By spraying neighborhoods, the residents believe that the mosquito problem has been addressed. With this false sense of security, residents lose motivation to look for mosquito sources around their yards and neighborhoods. Without source reduction, any temporary relief from mosquitoes is lost when the incubating larva emerge in the following days—affected by neither the now-decimated (and slower-maturing) predator population nor the airborne toxic chemicals.
  • Emboldened residents continue risky behavior and expose themselves to daytime-biting Asian tiger mosquitoes. This type of mosquito is inactive at night and is thus generally unaffected by community spraying efforts. It’s also a carrier of West Nile virus and Eastern equine encephalitis virus.
  • Spraying breeds pesticide resistance. This means that should a disease like malaria or dengue fever appear in the mosquito population, the last-ditch defense against human infections will have been compromised.


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