Bt
       Bt is one on the least dangerous pesticides known to us at this present time.  Bt is a naturally occurring bacillus and it is amplified in laboratories to complete the job with better results.  There is, like with most good ideas, a problem.  Bt is a chemical that is for certain insects and there has not yet been a version created that will help the mosquito problem.

Chlordane
       Chlordane is a broad-spectrum pesticide.  Broad-spectrum pesticides are designed to kill more than one species, including mosquitoes.  This means that if they spray Chlordane, the non-targeted organisms will be affected as well.  The impact that will occur on the non-targeted organisms cannot even be measured.