I recently completed a breeding project that produced a complete set of the "middle" plants (if you graph out all the plants, then draw a line diagonally between the two plants that can't be bred, those are the "middle" plants.) If your cross-pollinate two middle plants you get another middle plant.
Anyway, this gives me 23 plants that represent every foliage and flower.
However, I haven't seen those two bugs, so either I've just been unlucky or they want a specific plant - specific flower AND foliage.
That's what I'm trying to find out, if anyone knows. The name of the bugs might shed some light on what they like. If someone knows this, but needs info on another _bug_ (I've got the other 46) I can probably help.