Attached fly stitch is a variation of the Y shaped fly stitch. It can be used to fill leaves or to embroider pretty borders.
To stitch this, you will need to know how to stitch the fly stitch first. This is stitched between 3 parallel vertical lines.
Bring the needle up at A (line 1). Go down at B (line 3) and come back up at C (line 2). The working thread is below the needle.
Make a very short stitch from C to D by going down at D and coming back up at E.
This is the Fly stitch. If more such stitches are added below it, then the stitch is called attached fly stitch.
Now just like step 1, go down at F and come back up at D while the needle is below the working line.
At this stage, it will look like this. Make a short stitch from D to G. Go down at G and come back up at H.
Repeat till you reach the desired length.
The backside is also pretty and looks like this. This stitch requires a lot of thread. So if you are using it to fill large spaces, buy enough thread especially if it is a rare color.
The completed work will look like this.