All animal-fibered clothing and fabrics are particularly vulnerable to moth damage. Storing your caps in sealed plastic bags or in cedar chests will make all the difference. A few drops of cedar oil on a rag and placed in the bag with your woolens will confuse the moth's sense of smell and prevent them from chewing through the fibers. We also highly recommend the use of pheromone traps which not only limit the moth's presence but also let you know if you do indeed have moths at all. We prefer the Safer brand traps that are readily available online. If you're trying to control an existing infestation you can put your garments in a bag in the freezer for a few weeks and that will kill all phases of the moth's lifecycle.
We recommend dry cleaning your caps and Nekkers, especially if they have any fur in them like Samoyed, Qiviut or Angora. Certain yarns like cashmere and merino can be gently hand washed but our experience has been that most caps and Nekkers look better with a once a year trip to the dry cleaners. Your caps and Nekkers will naturally stay cleaner by virtue of the fact that most animal fibers wick dirt and moisture away from the head much more effectively than synthetic fibers do.
When you remove your cap never pull it from the top. Instead place your fingers under the brim of the cap and gently slide it off your head. This insures that the crochet stitches don't get stretched out. It's not that the stitches are all that fragile but pulling on the top of the cap over time will for sure stretch them out.