Rob
Here it is.The body is deer hair.Floatant keeps it buoyant. Not sure what the tail feathers are made of.The deer hair should not be clipped too close.The bug is the easiest to cast,lands on the water quietly and tied correctly dives under on the pull with an audible gerbubble sound.They were available yrs ago from LLBean until the tier either retired or whatever. At that time I found some elsewhere.But they didn't dive well perhaps because the deerhair was closely clipped.
Here's another bug I got at a Blowout made of foam material & tinsel that fishes similarly to the gerbubble.The hook is a little smaller than I'd prefer. I'd like to know who tied it.