You may have heard of the idea of using mothballs to drive away squirrels. When I first heard of this idea I was intrigued for all of about 60 seconds until I easily discovered that using mothballs for anything other than their intended purpose is not only illegal but a tremendous health hazard.
Mothballs are saturated with either one of two pesticides, Naphthalene or Dichlorobenzene. Long term exposure to naphthalene may damage or destroy red blood cells, causing a condition known as hemolytic anemia. Long term exposure to Dichlorobenzene, of course, causes cancer.
So Some, not so bright, individuals thought of using mothballs in their attics as a deterrent for nesting squirrels, but apparently the pesticides are heavier than air causing the vapors to eventually drift down into the living space of the home where the occupants were breathing them in and out all day long.
Using mothballs in fruit or nut trees is also illegal and a health hazard. Bottom line is that mothballs are intended to be used only against the Tineola bisselliella, otherwise known as the Common Clothes Moth. Other than being locked in a foot locker full of cloths in the basement or in a box of cloths kept in a mini storage unit, you should not be using mothballs.
For a much better method of getting rid of squirrels in the house read this article: How To Catch A Squirrel