In July and August there have been three positive cases of West Nile virus in humans in York and Montgomery counties.  There are no human positives in Chester County, yet, but there have been 25 mosquito positives http://www.westnile.state.pa.us/surv.htm#humpos, and WNV has been identified in mosquito pools in Upper Uwchlan and Uwchlan townships (along with a few others).  I hate mosquitoes.