This is a detailed history of the Heddon Crazy Crawler Fishing Lure. As you can see, the different colors seem to trigger different responses from the fish.
The Crazy Crawler series 2100 was introduced in 1940, maybe 1939, with a length of 2-3/4″ and a weight of 3/4oz. This lure was originally produced by Donaly Lure Co, but Heddon bought the patent sometime in 1939. This fish catching lure came in seven cataloged colors originally, but was ultimately offered in eleven cataloged colors. The 2100 series was produced until 1957, when it was ultimately replaced by the tenite series 9120.
The “Small” Crazy Crawler series 2120 was introduced in 1941, with a length of 2-1/2″ and a weight of 1/2oz. It can be found in a conetail version with just the Heddon name printed on the belly, typically known as the earliest 2120 model. It came in the same colors as the 2100, but disappeared