I'd outline the butterfly, then quilt along a few of the lines in the wings. That would secure your batting a little better and add dimension to the quilt. For the larger caterpillar I'd outline it including the segments, then outline the eyes. I'm a novice at FMQ too but discovered I do better with an outline than I expected. You might want some meandering in the white area as well.
Cute quilt. Is the model the recipient?