(1688) After a lapse of another few days I was confirmed in my opinion , for little black Flies had come out of the cocoons , and were walking and flying about in the glass tube .After which time I have several times confined these little Worms that I took out of the cheese , in glasses enclosed , and I have always found that in changing , little flies emanated therefrom , unless I had locked up little Worms that had not yet their full growth : when they thereupon died without changing .This refers to the cheese - fly , Piophila casei ( Linn .