Cecil my panfish have been eating beetles for a few years. Originally I tried dumping dead beetles from the traps but they didn't seem to like them. They smell pretty rank after a little while or maybe the fish are looking for some movement from the beetles? Keep trying. A simpler feeder might consist of a good Trap/attractor on top of a long PVC tube which dumped an inch or two above the water. Japanese beetles are bad fliers and I think if they fall for a foot or two and only have a few inches to recover before being trapped in the surface tension of the water they are fish fodder.