Yes, cats can eat Christmas tree needles, but it is not recommended. Christmas tree needles are not toxic to cats, but they can cause gastrointestinal problems, such as vomiting and diarrhea. Cats may also get their whiskers stuck in the needles, causing them to have difficulty grooming themselves. Additionally, the sap from Christmas trees can cause an allergic reaction in some cats, causing them to scratch or chew at their skin. If you have a cat, it is best to keep the tree out of their reach, or at least keep the area around the tree free of needles.