Match the 'hatch' so to speak.

When I first had HSB in my main pond, years ago, they would hit whatever you threw in while they were pellet feeding.

The current crop of HSB I have in my neighborhood retention pond will only hit pellet feed, while feeding, and nothing else. So you have to fish with something that looks like a pellet.

george has been instrumental in making pellet flies. Some have taken panty hose material and stuffed them to imitate a pellet.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."