Carl was the master of mid west caddis flies. He spent countless hours studying them on the Muskegon River. Back in the day, the Muskegon River was considered a laboratory when it came to Caddis Flies. Dick Pobst was also very familiar with the Muskegon, he owned the Orvis Shop in near by Ada.
BTW, there is an excellent book written by Carl Richards specifically on the Muskegon River Caddis flies, if you can find a copy. I'm not sure how many copies exist. The first edition had individual photos hand pasted in the book. There was a second revised edition that had printed pictures. The book is a treasure trove of info.