Tiny Baetis mayflies are perhaps the most commonly encountered and imitated by anglers on all American trout streams due to their great abundance, widespread distribution, and trout-friendly emergence habits.
Latex? I remember in the seventies...
I can report that Mike Lawson points out this creation, to be a good looking pattern he accepted years ago only to find out it doesn't catch fish!!
...an example of man's trying to imitate trout food the way he sees it instead of the way it is believed to be visualized by the trout."