Surge in black flies in Maine

[MichaelJ]

Apparently the results of years of working cleaning up rivers in Maine is to have made an excellent breeding ground for black flies.
Full boston.com article

Many species of the gnat-sized insects are sticklers for cleanliness. When Maine's rivers were filled with contaminants from paper mills and other industries, only the hardiest black flies laid eggs in them. Now, rivers and streams are progressively cleaner, providing ideal breeding grounds for the annoying pests.

 

[David Metsky]

Sorry, but Peakbagger beat you to it: http://www.vftt.org/forums/showthread.php?t=23319