Butterfly Slip Stitch Pattern

How to knit the K1 uls.
Take the right-hand needle under the slipped threads, then pick up the next st on the left-hand needle and knit this st and the slipped threads together.

Pattern
Cast on a multiple of 10 sts, plus 9.
Rows 1, 3, 5, and 7 (RS): Color A, K2, *Slip 5 wyif, K5; rep from * to last 7 sts, Slip 5 wyif, K2.
Rows 2, 4, 6, and 8: Color A, Purl.
Row 9: Color B, K4, *K1 uls, K9; rep from * to last 5 sts, K1 uls, K4.
Row 10: Color B, Purl.
Rows 11, 13, 15, 17: Color B, K7, *Slip 5 wyif, K5; rep from * to last 2 sts, K2.
Rows 12, 14, 16, 18: Color B, Purl.
Row 19: Color A, K9, *K1 uls, K9; rep from * to end.
Row 20: Color A, Purl.
Rep Rows 1-20.