Abstract: A method and apparatus for controlling tension of lay-in warp yarns knitted on a warp knitting machine is provided for knitting a fabric having lay-in yarns with varying intermittent spacing between horizontally corresponding lengths thereof. The lay-in warp yarns of a warp knitting machine are preferably dividedly passed by two or more flutter bars which are simultaneously moveable in cooperation with one another to simultaneously and reciprocably increase/decrease and decrease/increase tension on lay-in warp yarns passing thereacross. Alternatively, the two or more flutter bars may simultaneously and reciprocably increase/increase and decrease/decrease tension on the corresponding lay-in warp yarns passing thereacross. Each flutter bar is a shaft with a parallel and spaced-apart contact arm for contacting yarn. The flutter bars are connected such that rotational movement by one flutter bar causes rotational movement of the other flutter bar.