WA state web site:
Quote
Shooting tree squirrels may be helpful if a small, localized population of introduced species is problematic. For safety considerations, shooting is generally limited to rural situations and is considered too hazardous in more populated areas, even if legal.


The Eastern Gray Squirrel has been invading WA since 1925
http://en.wikipedia.org/wiki/Eastern_gray_squirrel

My experience is that even if it is legal to shoot, the neighbors don't want to hear it. And at night, the wife does not want to hear it.

There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. -Ernest Hemingway
The man who makes no mistakes does not usually make anything.-- Edward John Phelps