We have all seen the empty shelves in the toilet paper and hand sanitizer aisles amid the novel coronavirus pandemic. Now, we can add another item to the list of things in short supply: It's hair color.Walmart CEO Doug McMillon said shoppers have turned their attention to dye.With salons closed for nearly a month, roots are beginning to show for some people, and that means coloring their hair at home as people shelter in place.Research firm Nielsen says sales of hair coloring products are up 23% from the same time last year. Other hair care items are also big sellers. Nielsen says hair clipper sales have increased by more than 160%.The first shopping wave happened during the week ending March 7. That's when Nielsen data showed hand sanitizer sales going up 470% from the year before, while aerosol disinfectant sales soared 385%.Suppliers say there is plenty of stock coming in, but people continue to stockpile and that's leading to empty shelves.