Beaded Alternating Up and Down Buttonhole Stitch is a variation on Up and Down Buttonhole Stitch which follows a curve well so you work in circular pattens or if worked in lines makes a great border pattern too!
With this stitch the beading is done during the stitching process not added afterward. The trick is use a size 26 tapestry needle. Since the eye of a tapestry needle is long you can thread perle #8 and Perle #5 through the long eye. However the needle itself is thin which means you can add a bead to your working thread as you stitch.
How to stitch Beaded Alternating Up and Down Stitch
Starting this stitch with a regular buttonhole stitch
For the next part of the stitch, insert the needle as illustrated and take a bite of the fabric with the tip of the needle pointing upwards. If you are used to working buttonhole stitches this feels wrong as the needle points in the other direction but it is right.
Wrap the working thread under the needle and pull the needle through the foundation fabric. As you pull the needle through pull the needle towards you instead of away from you. As you do this hold down the loop that forms with the left thumb to prevent it slipping. This loop forms the bar at the base of both stitches.
Thread a bead on to your working thread.
Work the next pair of stitches pointing on other side of the line.
Continue along the line adding beads between each pair of stitches as illustrated.