This is a good question. Since nobody speaks squirrel that I know of, the theories are that they chew because they are rodents and their teeth are always growing, so they have to chew on something to grind them down. The other theory, which I subscribe to, is that its sweet tasting. This goes back to the old lead paint young people dont remember, but in the 50s paint had lead in it and children would chew on it because its sweet tasting. Caused significant health problems. Regardless, they do serious damage. Check out the attached pictures. Critter Quitters protect them from this because they get no benefit from chewing them. Amazon or Homedepot.com