From my admittedly very limited copperband butterfly experience (which consists of keeping one specimen for about 4 months or so, when it inexplicably stopped eating and expired), and from reviewing lots of threads about them, the one thing I would say for sure is that they love feather dusters, and it would be a very unusual specimen that would ignore them. Mine was in the display tank for literally about five seconds before it took out the one feather duster I had.