Poor or failed mosquito control; Mosquito-carried disease control efforts:

Mosquito spraying cause of tree infestations
Insects Attack Oaks in Savannah

Outcome Studies: Mosquito control, WNV control efforts
Winnipeg, New York City, Greenwich, Stamford Connecticut, Florida, Texas, Maine
Outcome Studies

Survey of mosquito control practices and less-toxic alternatives
http://skipper.physics.sunysb.edu/mosquito/mosquito2/Mosquito2.htm
Survey of Mosquito Control Practices and Less-Toxic Alternatives

The Cicero Swamp Study -- Are mosquito spray pesticides worsening the encephalitis problem?
http://www.chem-tox.com/brevard/encephalitis/
Cicero Swamp Study

Using pesticides may do more harm than good
www.meepi.org/wnv/overkill.htm

EPA - pesticide poisoning handbook
www.epa.gov/pesticides/safety/healthcare/handbook/handbook.htm