Apparatus for controlling composite effect yarn with enlargements, such yarns being formed by twisting components thereof by a driven hollow spindle, comprising a guide for the composite effect yarn disposed a substantial distance downstream of the driven hollow spindle, driven means for pulling the composite effect yarn from the spindle and forwarding it in a span under tension to the yarn guide, means disposed immediately upstream of the yarn guide for catching composite effect yarn in said span having abnormally large enlargements so as at least to slow its forward progress, means for detecting a decrease in tension in the composite effect yarn in the portion thereof between the yarn feeding means and the means for catching abnormally large enlargements in the composite effect yarn, and means responsive to said tension detecting means to stop the feeding of the components into the spindle upon such decrease in tension in the composite effect yarn.