I never heard of him but I googled Ed Sens for you and up came a book by Ernie Schwiebert. Towards the bottom of page 41 and onto page 42 describes the fly and give recipes for his big wet flies he used to imitate big stoneflies. HTH
http://books.google.com/books?id=qbxRv9ywtP0C&pg=PA41&lpg=PA41&dq=Ed+Sens+stonefly&source=bl&ots=CLS_yjhSN1&sig=YlOYviu__DHGkp_TN1BkDJ68zzM&hl=en&ei=v_IhTcjaD4L48AaRsdDVCw&sa=X&oi=book_result&ct=result&resnum=1&sqi=2&ved=0CBMQ6AEwAA#v=onepage&q&f=false