In 1941, the Webelos rank was created for 11-½ year-old boys. The first Webelos badge used the emblem today known as the Arrow of Light and was worn on the left pocket flap. Den mothers became optional Cubbing leaders in 1936, eventually becoming a registered position in 1948. The "Bob Cat" rank was introduced in 1938 as the entry-level badge for a new Cub, with a pin for non-uniform wear. Until 1942, boys joining Cubbing at any age were required to work their way through the ranks, first earning Bob Cat, then Wolf, Bear and Lion, wearing only their current rank and arrow points. After 1942, Bob Cat became a joining rank, then the Cub Scout progressed to the next rank for his age level and all earned rank badges were worn. In 1945, the Cubbing program was renamed to Cub Scouts. 1947 saw the uniform change from knickers to trousers. The age groups were changed to 8, 9 and 10 in 1949. "Bob Cat" became "Bobcat" around 1950.